There are many negative factors to consider.
You will never do just one cycle.. because even though you make "amazing" results first cycle.. they will go away fast, you will most likely do multiple cycles and even think about cruising ( which is using low dose for long periods of time).
It will also become expensive, a good cycle is around 500-700$ and that is already at a low cost from a trustable source, if you get it with inflated cost you will easily pay over 1,000$ for a good cycle..and the gear will probably not be half as potent as it should be.. cycling is expensive and not worth it unless you have a steady cash flow coming in.
Long term sides are also very high, yes u will feel like a god etc make good gains.. but 5-6 months later you will crash hard, test levels will be lower than before starting, you may develop gyno during cycle or even up to 1 year after no use..many have reported they cannot maintain sex drive or get hard..many have long periods of depression..
Even running a cycle "perfectly" will yield hiccups, what happens if you start developing gyno and u run out of nolva? now u have to find a reputable dealer mid cycle and have a 50/50% chance of not getting real nolva.. and what if u spend 100-200$ on nolva.. and gyno gets worse ? where are you going to buy or find real letro? many things will happen, and even after having the finest cycle on paper and on hand.. anything can happen to set it into chaos..its happened to me.. and i have cycled 4-5 times.. cruised even.. there have been times i had to have an emergency and purchase additional compounds...
At your age you will most likely be on trt near your 30s as well depending on length and dosages used on your cycles.. are you ready to inject for the rest of your life? is that really wat you want? also the chance of conceiving a daughter are higher than normal for steroid users..all my friends have had daughters.. all been on test for 3+ years...
Now what is a good time to take test? I would do it after 30's even 40's maybe after kids..that way i wouldnt have to worry about shutdowns or sperm value.