AS long as their fully developed and easy to squeeze the puss out, then it's ok. I then advise putting some kind of antiseptic or similar on the wound to help prevent more
shit going in there after the wound is fully open. I've used tea tree oil in the past, and it's gold. Make sure you don't have to squeeze them too hard, otherwise, that's how scaring can occur.
Try to keep your hands clean as well, when you're popping. Cause it has oil etc on it and you don't want to get that in there. mayeb if you wash with soap or soemthing before hand it should be ok.
In the past i've used papaw cream as well, to put on afterwards. Which is just like a skin ointment or balm. So that's worked for me in the past. Its important not to force the pimple out though, that's when you get some nasty scars. So don't be tempted until it's
ripe
Also, pimples are commonly formed by a hair being trapped under a layer of skin (or something like that

) so it's good to physically exfoliate your skin, by rubbing a relatively coarse material on their (brushes work). To get rid of the dead surface skin blocking the hair from coming up. Although you don't do this once the pimple is formed, only on surfaces where there are no pimples. You shouldn't irratate them. Or you could get some kind of beauty stuff which chemiaclly does it, but i haven't really used that before
So pop when they're ripe and dis-infect the wound and put some kind of balm (healing) on it and it should be pretty good to go and heal almost overnight?
You can try to physcially pull the offending hair (once exposed by popping), our of the folicle as well, just in case.