I've just had a super fast read through and just want to make a quick point . . . The steroids are the icing. You need to make the cake first. There is no magic point. It's an ongoing week in week out year in year out regime. Changing routines and even taking a week off is all part of that regime. Steroids will just help you recover from lifting heavier and harder and it will still take time to get to heavier and harder.

You can get by without a spotter.
Squats are probably the best exercise you can do and if you do sets of 20 reps, then the weight shouldn't really crush you. Save the 2 to 5 rep heavy stuff for later.

How often do you take time off?

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A lot more than most but then again I am 54. It's really an individual thing. I'm just saying that if you or anyone else stops making progress you or anyone else should consider the possibility of over training rather than automatically increasing the workload yet again.
As you're about to start benefitting from steroids this might not apply in a few weeks though.