Very roughly, you can plan out a number of cycles, like how the BBB 3 Month Challenge is a multi-cycle but definite duration plan. In general, one would figure out what your workouts are going to be for, say, 5 cycles, set an appropriate TM and then go through those 5 cycles. After that, reset the TM for the next program (that is, the next planned block of cycles). As Jim indicated in his reply above, one might "test to make sure the TM is correct between each program." Most commonly it seems the TM should be set to 85% of 1 rep max, but for some plans it may be better to do 80% or whatever. You might need to think about what TM will make sense for you and the cycles you plan out. I think the easiest way to test that that the TM is appropriate when you want it at 85% is to work up to a set of 5 reps at the proposed weight.
If you dig through what Jim says about "Leader" and "Anchor" cycles, I think you see he generally recommends leading with cycles that are higher volume but lower intensity, then ending with lower volume and higher intensity cycles. That is part of what you might do when planning out 5 cycles, as by having the first few cycles include higher volume supplementary lifts and not pushing for PRs, then for the last cycles cutting back on the supplementary work and pushing for PRs.
Simplest for now is probably to stay the course as you have planned and just reset after your 5th cycle. Between now and then you can consider finding or planning out a program consisting in a block of cycles (Jim has many recommended programs and lots of info on programming in the forums on his own site), or just keep at the program as you have it and just reset periodically (as with 5 forward, 3 back). Most important, of course, is that you keep at it and stick to the core principles (start light, progress slowly, etc.).