I begun with 15 minutes in BM.. and yes, Bathmate can do really high pressure, so do the smart way or the highway!
The bad thing with BM is that you don’t have an gauge, so you must go by feel and be careful with the high pressure so you don’t over do it.
When you have entered BM I suggest you pump up 2 times with 30 seconds between pushes, then every 5 minutes you pump just a small push not that hard as you do in the beginning.. just to have a steady pressure thru your entire pump session. If it feels to much just press the seal at the front..
I do my stretching, jelqing, ullis and squeezes before I enter the BM.. and then 50 light jelqs after pumping. Do what feels best for you and be careful in the beginning. A good thing is to do kegel exercises when you pump.. but the main thing is that your dick is gonna get used with your new toy..
I hope that help you on your way :-)