As a guy that likes to bring maximum pleasure to any guy I top my suggestions are this:
1) get him really turned on
2)begin to lube him and finger him with one finger as you continue to stimulate him elsewhere (kissing, working his nips, etc.) [make sure fingernails are well-trimmed!]
3)slowly add another well-lubed finger into him and keep adding a little more lube
4)rachet up the stimulation with sucking on his most favorite parts as you add a third finger clustered close to the other two
For me at just over 6" around if I can get three fingers in, I know that he is ready to receive me without undue pain. For some guys this may take several sessions. But by the time he is ready, he will want it so bad that it all works great. Keeping up the stimulation elsewhere distracts from the gentle stretching and makes it a hot prelude to something even hotter.
For someone who is 7" I would recommend getting at least the tips of all four fingers in before attempting entry. The most important thing for a good larger top is to be patient and go slowly. When the guy is ready, I lube my cock liberally, and gently but frimly insert just the head and then wait. Keep kissing him and wait till he's ready for more it may take a few seconds or a few minutes. And sometimes you will need to go out again, wait, and try again. Assure him that it's OK. If you prepare him well, though, he will be ready for more and more in vey short order and then you can both launch off to heaven!