Just ensure deepthroat is not on your profile. That way they cannot expect it.Put a note on your profile to reflect what sizes are possible for penetration.That way everything is clear.
Im struggling to give oral to bigger cocks they often want deep throat and I literally can't go that far down onto their erection.Just had a wide big guy I think he was disappointed with me I had to keep stopping I nearly gagged.Never have this problem with smaller cocks and can go all the way down easily.I use much oral gel to make it taste and feel good .I can't also take penetration from the big ones at the moment too, had to stop sex with same guy i was in agony.