I wouldn't worry about the transition to standing just yet. When he starts to want to be like dad is when I would let dad step in and show him. That or when Dad is primarily the one taking him potty in public places. Dad won't want him sitting in the men's room, lol.
However, be sure that whenEVER he does start to stand, that you have him use a step stool. My son dropped the toilet seat on himself b/c I didn't think about it happening and he was tall enough to not need the step stool to get it into the bowl... But apparently NOT tall enough to keep from getting "pinched" by a dropped lid. My BIL and SIL are both nurses. One of them has worked in ER and they get visits due to this on a REGULAR basis.