No idea what time zone you're in and if you have already started or not...
A mushroom trip lasts at least around 5-6 hours and transits often into a nice afterglow. We cannot predict how your trip will turn out and it matters a lot for how you come out of it. I sure as hell have had trips with mushrooms that would make me cancel something like a doctor's appointment in the morning. The tiredness wouldn't even be the biggest issue, there are other ways to feel sketchy. Don't you have other opportunities than tonight? If at all possibly I would opt for a time when I wouldn't have to be at such a lame responsibility/appointment in the morning. It just would not be optimal for the mindset. But if you are okay with the option of cancelling or feel like this moment is so much better than any other that you would just deal with an impracticalities I guess you *could* go for it.
Don't ask us to decide for you though, that is not how this forum works (I know you did not actually ask that).
Either way, if you end up laughing uncontrollably while your GP is looking at your asshole, let us know.