If I can paraphrase the excellent advice given by mikechar here on the forum....
Press slowly at first, increasing the pressure to maintain drops of whey running out, not a stream....
Flip and rewrap about every half hour....
Keep increasing the pressure as needed to keep the whey being expelled slowly, never in a stream....
By the time 2 hours have elapsed all whey should be expelled and the rind knit.... Flip and rewrap for overnight pressing....
At this stage basically it does not matter how much pressure you use.... but here is what I use....
Cheddar and other salted, milled cheeses - 3.5 to 7 psi (the drier it is, the more pressure needed)....
Other semi-hard to hard cheeses - 2 to 3.5 psi....
Semi-soft to medium cheeses - 1 to 2 psi....
I have found that the instructions in most cheese recipes are less than helpful to just plain problematic.... Pressing too much, too early, traps whey and causes acidic centers with cracks and voids, and even a crumbly texture.... Correct initial pressing is critical.... Hope that helps....
Bob