Tren is a really strong drug. I would hold off and get the most out of less before you move up. The more you cycle, the less effective the same dose of gear will be. You'll find that as you cycle, you slowly require more and more gear to continue progressing. Part of this might be that your body gets used to X amount of hormone and part of this is probably due to the fact that the bigger you get, the harder it is to continue growing. So the smaller you are, the less it takes. Why not get the most out of less? If you can gain 15 lbs in a test only cycle, why throw 2 or 3 compounds in? Its not like you will then gain 45 lbs by doing so. Your body is only going to grow so fast. It moves at its own pace and in order to build a massive physique, you need to play this game for YEARS. 

So I'm sure you can see where i'm going here. Leave yourself as much room as possoble to increase. Get the most you can out of the least amount. So lets take a guy who has used small cycles and slowly climed to 220 lbs, fairly lean. THEN he added tren to the next cycle. Tren is a very strong drug and as someone that has stuck with drugs that are milders, our 220 lb guy will will a much stronger effect and produce much better results than the guy who has already been running high doses and strong compounds just to get to 220. 

Another reason is, its ideal to use different drugs at differetn times. It is not going to be beneficial to use the same cycle year round, every time you run gear. So in the off season when growth is the goal, I'd prefer to use the more anabolic drugs and then save the tren for when I am dieting down to my leanest body fat % and most at risk for losing muscle. 

Tren can be run in an off season, sure, but I would not jump right to it if you have only used steroids one time before