20 weeks is way too long for a first cycle.. First cycle should be 12 weeks.
You don't list the dose of dbol, unless I missed it? Either way, 6 weeks is much too long for dbol first cycle. I'd even go so far as to say dbol isn't even needed in a first cycle. If you insist upon it, 30-40mg ed for 4 weeks tops.
Honestly for a first cycle 400mg of test is more than enough. Add the dbol if you like, but I would't even bother for first cycle
Other questions were left un answerred as well. .Age? Experience?
Understand that your diet is even more important then your gear.
Don't be one of those guys who once they go on a cycle, they double their work load in the gym lol.. First cycle, your training should be the same as what worked best when you were not on gear.
Follow what ABmonkey said.. don't take your aromasin until you get blood work or sides. I'm going to guess you likely won't even need it esepcecially if you get rid of the dbol (or stick to 30-40mg for 4 weeks) and lower your test to 400mg.