For me, I only roll with Test C or P and sometimes Tren. If the bottle is 10ml, I cycle 2 bottles for 10 weeks. If it's 25ml, I cycle 1 bottle for 12 weeks. That leaves no open bottles at the end of cycle (no reason besides personal preference).That's also in general. Depending on particulars, I'll change things.
At bare minimum, time off equals time on.