Whats up guys?

I've decided to start my first cycle pretty soon here, I'm 26 years old and been working out seriously for about six years now, i'm 6'2 190lbs. my whole family is pretty small, I'm the biggest guy believe it or not but I want to get bigger, my goals with this cycle is to put on some serious mass. I'm thinking of running deca , dbol , and test, any suggestions toward my dosages would be appreciated as well as information on injecting. I've watched a few videos and plan on injecting just above my glute but do I really need to try and draw blood to see if I've hit a vein? they say do it in the videos but any video i've seen of someone actually taking steroids they just insert the needle, inject and pull out. anyway, here's what I plan on stacking;

300mg deca inject per week, 10 weeks
335mg test cyp inject per week, 12 weeks
20mg dbol oral per day. (10mg morning 10mg night) 8 weeks

the reason for the inconsistency with the amount of weeks is because I was told I should try and run my test two weeks longer than deca and the dbol is 8 weeks supply unless i drop down to 10mg a day

thanks in advance for any advice or comments