Student or Learner
Doctor says that my treatment will last for 18 months. SO he says I can't exercise during this period, but it seems "he would allow me to exercise after 6-7 months of treatment" or "after half of the treatment".
If your treatment is due to last for 18 months, half the treatment period would be nine months, not seven or eight.
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.
How to say it correctly?.
The doctor says that my treatment will last for 18 months. He says I can't exercise during the first part, but after 6-9 months, he may allow me to.
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.