yeah after pct, maybe 2 or 3 weeks your motivation plumets because you're not as strong as you were and you need to be mentally strong to keep going and push through it. that, imo is the only reason to be against dbol only cycles.
you'll not lose your gains if you continue to work hard though. that's where people go wrong and claim to lose all their gains.
as for keeping all the weight you put on during the cycle, your best bet is to take an A.I. with it, that way the water weight will be less and you'll have less to lose post cycle.
best way to use them and NOT be wasting your money would be to do a shed load of research into what you're doing and you'll have a good understanding of what you're looking to do.
that said you seem dead set on starting on monday so I'd imagine this will fall on deaf ears