Remind can be used with two prepositions “of“ and “about“ but each is used for different situations. “of“ used of memories, connotations His voice reminds me of my brother's. Her eyes reminded him of past memories. And about is used when we're talking about a future event. “She reminded me about our holiday.” But if there is a sentence coming after remind we don't use about “She reminded me when the meeting starts.” Hope that helps **** I don't get used to is rare but isnt grammatically incorrect. If we're talking about a situation we're not used to “I'm not used to...” is the most accurate form. But I don't get used to can be used for general descriptions like “I don't easily get used to new cities.” though “can't” be used in this situation as well.

You can say "remind her about when the party will start. You can also say, " remind her of when the party starts." I'm not sure about the answer to the second question but it sounds weird the first way and the second way sounds correct.