If you're keeping your penis pointed down (which you should) then the front of the crotch will get wet first. If with that your front top is wet, your diaper is probably very soaked and is at risk of leaking. (it WILL wick upward a bit, but it's fighting gravity) What you need to be thinking about more is in the back under your cheeks, that's where disposables like to leak. Different things change the risk factors. Sitting down increases your chance of leaking there for example. You'll have to figure out and get used to what's best practice for what you're wearing. (and getting a good, leak-resistant fit will require some time, experimentation, and practice)