250mg of testosterone a week is a big increase from natural but don't expect to gain 10kg in 12 weeks
Also no need to run dianabol at the start either, you're using sustanon which contains a short ester. Save the dbol for when you're very lean
Sustanon will also give you a lot of sides unless you're pinning it every other day due to hormonal fluctuations. If you're pinning once a week you're getting 250mg all at once, in 4 days time you will have just 165mg circling your system and just 80mg by the time you go to pin again in a weeks time. So really you want to be injecting 0.5ml every other day to keep hormone levels stable (lots wasted in the needle), 1ml (75mg) of propionate every other day (half as much lost in the needle) or weekly injections of enan or cyp
Imo sust isn't worth it unless you're taking in a gram a week, it's also expensive