Apply ASAP. In the mean time get your application process for school. Remember 60 days after opt expiration is when your Sevis/f1 terminates. Get a i20 before that.
You can continue working with TPS was until March 2020. Or until the expiration. F1 will need to be maintained at the same time if you want to be in status.
GC application can be processed anytime provided that you have a company who will do it. No need to wait on h1b. That takes 1-2 years currently, during that period you have to somehow maintain legal status.
Best of luck.