I'd say new diet and training routine would be the biggest one because you can just go on and on about how well this new routine is working for you lol.
But I think the best way is to kind of hide your size before you do the cycle. For instance don't wear tight shirts and such because then every lb is noticeable. If you usually wear baggier stuff you won't look much bigger even with 10 more lbs. Then when they see you with a shirt off or something you can say it took a long time (longer than 8 weeks anyway lol) to build it up.
I get that question in the gym all the time when im "ON". I tell people creatine and protein shakes...some believe and some dont. Then the next day I see some people taking some of the supplements I told them about, lol.