That's a tricky question because improvements in different symptoms took vastly different amounts of time, and my improvement times were very different from my daughters'.
My daughter had some improvement in her condition within 6 weeks of starting Valcyte. I didn't see much for 6 months. She was able to sit upright in the car longer as soon as she got some OI treatment. Since I didn't get OI treatment at that time, my ability to do the whole long car ride sitting upright took much longer -- maybe 8-9 months -- and was strictly the result of Valcyte, since that was all I was getting at the time.
Getting appropriate OI treatment made a big improvement in functionality for me. It didn't change my PEM, but I was able to do more because I could be upright more and walk around more without my BP and HR going nuts. Theoretically, any of us should be able to get OI treatment locally, but I imagine many of us have the same problem I did -- we don't have severe, classic POTS, so our local docs either don't recognize it or refuse to treat it as "not serious enough to warrant treatment". A lot they know.
My daughter went from nearly (probably should have been) housebound and heading downhill rapidly to about 90% functional in approximately 18 months. She takes a lot of treatments to stay there, naps more than most people her age, and is cautious about activity -- she doesn't do aerobic exercise, for example. She has done several continuous days of day-hiking a couple times a year for several years now. We don't think she gets PEM anymore, or if she does it's mild by our standards. She can tire more easily than others her age, so she may still have some exercise intolerance or effects from her OI. She is not cured, but is able to do most things people her age do.
I went from bedbound and unable to read a book to able to work full time from home and take care of all my ADL's including shopping without a wheelchair in about 5 and a half years. It came in fits and starts as my specialists tried different treatments. We just keep picking away at symptoms, giving me another 5% functionality here, another 10% there. The biggest was antivirals, though. Valcyte and Valtrex improved my condition by about 50% (from bedbound to mostly housebound) in 2-2.5 years. OI treatment after that gave me another 10-15%. Other things give me lesser improvements, but many little things add up.
The biggest effect on PEM for me is from high-dose CoQ10 (1200-1800 mg daily). I was doing noticeably more within 6-8 weeks of starting the high dose.
My current specialist keeps picking away at my symptoms. She keeps an eye on my condition -- pathogens, immune changes, thyroid, OI, and so on -- and adjusts my medications/treatments as necessary. My condition does not stay stable at it's best level. I need regular management. I get new pathogens or reactivations of latent ones. My immune system is not good. My system changes as some things seem to be healing while others continue to deteriorate.
For me, it's not a question of seeing the specialist to get a one-off treatment and I'm done. I don't think ME is like that. We don't have a cure. There's no one magic fix-it treatment. Like a number of other chronic conditions, my ME needs on-going medical management to keep me functioning as best I can. Most of this is done by phone appointments and labs my specialist orders and I have done locally. Irregular treatment would not give me the on-going management I need to stay functioning at the level I do now.
As far a cost is concerned, I'm finding it to be cheaper and less physically demanding to travel by air to see my specialist once or twice a year than to try working with my local doctors. I wasted SO much money and energy seeing local cardiologists, endocrinologists, GPs, etc who charged me lots of money and did nothing for me. It was also physically and mentally exhausting to make trip after trip after trip and get nothing but insults. A well-planned trip by plane once a year turns out to be less physically demanding than repeated trips to local doctors.
My specialist costs no more than my local doctors and is covered by my insurance, so there's no extra cost there. Most of the labs are covered by insurance as well. The cost of the few labs that aren't covered is more than made up for by
not paying local doctors over and over. In fact, last year my husband's medical expenses were higher than my daughter's or mine and he doesn't have ME!
Right now,
the biggest out-of-pocket cost related to ME is supplements which are not covered by insurance. My specialist tries to avoid recommending those any more than necessary, but sometimes there isn't an insurance-covered medication that accomplishes the same thing. For example, I've been on and off
low doses of Equilibrant. I'm better on it than off it, so I take it. My daughter's NK cell function stays normal with inosine, so it's worth paying for. I wouldn't be able to work full-time without CoQ10, so I choose to pay for it in order to be able to support myself. None of these supplements are cornerstones to my specialist's treatment plan. If I couldn't (or chose not to) afford them, she would do her best to find ways to help that I could afford.
All that said,
ME/CFS specialist treatment is not a magical cure for me. It's a very, very delicate balancing act to keep all my symptoms under control sufficiently for me to have a rough semblance of normal life -- support myself (if not at the level I could pre-ME), take care of myself and my home (with definite limitations), and interact with my family and friends. If I don't keep up with
all my treatments/management religiously, or if I catch something, it can all come crashing down. I don't fall back to long-term bedbound; I
am past that. But not keeping up with my hydration protocol, missing medications (or some supplements), not staying within my (new) energy envelope, straying significantly from my diet, can be a disaster. I can't keep up with my work, am back in bed by mid-late afternoon, and need a wheelchair outside the home.
I'm grateful that my specialist is willing to work with me to tweak every little thing to allow me to walk this tightrope of relatively normal function, but I'm under no illusion that I've beaten ME or that I am free to do what healthy people do. I'm willing to perform this balancing act because I
want to be able to think straight, support myself (after a fashion), and take care of my ADLs as much as possible. If this is what it takes to function as 'well' as I am now, I'll do it as long as I am able, but
I'm not going to pretend it's easy or that I'm not aware every waking minute of the limitations ME imposes on my life.