The side effects you have suffered will wear off one by one.
Hopefully you get a decent break before the periods return. The average is a 5 month wait.
But ine were back as soon as my remaining ovary could give me one. The wretched beast !! so I had a period 8 weeks after that last implant went in, thus 4 weeks after I should have had the next implant if I had had one.
Some ladies have an even longer wait, and for a small number of ladies their ovaries do not wake up and they don't have another period and they stay in a state of menopause. Each of us is different, so my advice is once you are feeling better from the side effects, live life to the fullest you can till the return of the evil endo.
The 1st period after being shut down for so long can be sludgy brown and might also be quite a long lasting or heavy period, and not a nice event especially when you have had a break and got used to not having them.
As for the follow up gynae appointment. I never got one. I suspect it depends on whether you were having the drugs before a surgery or after. Or whether being on the drug did improve your endo or suspected endo, and deciding what to do next. ie Mirena Coil or BC Pills etc.