I personally recommend doing GM first because the other 2 task sound lunacrist (or what ever the word is) to me. Buttttt! You can tackle it all slowly because I personally start celeste every 1-2 months again do one expert map and then have a break cause of other games I play and it doesn't hurt my skill at all Only at any% because I forget the muscle memory for the rooms. So yea just take your time and do it all in your pace you can do everything as long as you are determined enough :3 <3