sustanon, like deca takes forever to 'kick in' for some users. If I were in your shoes I and wanted to only do a 6-8 week cycle I would go with test prop @ 150mg eod. Thats 525mg per week. The downside is every other day injections which probably would not be very pleasant for your first cycle. You would achieve faster gains, less bloat and it would clear from your system the fastest so when you started PCT you wouldnt have 3 weeks of downtime before you stop, and this would help avoid the slide into catabolism.
how about test prop@ 150mg/eod + 20mg dbol/ed for 6-8 weeks?
If you're stuck on the longer chain esters go for 10 weeks, and you would probably like 500mg sustanon a week as opposed to 250mg. You'll see gains on 250mg none the less.