As others have said, don't stress out about this. I've heard it said that no kid ever goes to Kindergarten in diapers, so you definitely have time for her to decide she wants to do this.
That said, I'll just share what we did. I have two girls now almost 4.5 and just over 3. My 4.5 yo has Down syndrome and I had heard not to even try with her until she was around 4. Plus, then I thought I could do both girls together, which is what I did.
We used the 3-day method. Did it just after Thanksgiving last year. Basically, plan to spend a full three days at home focusing on nothing except potty training. There is a lot of information out there about how to go about it, but the way it's laid out and the way I did it was to actually throw away all the diapers on the morning of the first day, so the child knows, and you know, there is no going back. Of course you can build this up as much as you want to beforehand, and I might recommend you get some videos - we had one with the Bear in the Big Blue House, but I know there are others people say the kids really like.
Anyway, that morning we threw away the diapers. I had two little portable potty seats we put in the living room, because that was where we were planning to spend all our time. But wherever is good for you that the child can get to easily. The big phrase we used was - You have to keep your panties dry! Keep saying it over and over. When there is an accident, you have her touch her panties and ask if she kept her panties dry? Reminder her it's her job to keep her panties dry.
Then, you push the liquids! Whatever she likes, juice, soda, special treat liquids - stuff you don't usually buy. Just keep giving it to her! Once she starts refusing to drink, you can give jello which is also a liquid. Then do the timed routine of putting her on the potty every 20 minutes. If/when she has an accident you act very disappointed. I have read where it is advised to have the child clean up, but I didn't do that. I recorded how they did, and gave stickers and made a big deal out of it when they did go. My almost (at the time) 3 yo was having some good success by mid-way through the second day. Eventually you want to move the potty near the bathroom so they have to think ahead and "run" to go when they have to. We always just reenforced having them "listen to their body". After the third day, the almost 3 yo was pretty much trained. Her sister that has Down syndrome wasn't very impressed about any of it (video, stickers, special fluids) and so we struggled with her for about a week, and then all of a sudden, she just decided she wanted to use the potty. For her (strangely enough) high fives were what she most responded to. We also read a lot of books while they were sitting on the potty (and still do if we are expecting a #2, or going out somewhere and we need them to go before we leave the house). That first few days I had them sit on the potty and watch their favorite movies too (while pushing the liquids). Then I made a big deal when they went, although they really had no choice since they were sitting right there on the pot (ha!).
As far as at night. The book I read recommended not going back to diapers or pullups at night either (we threw away all the diapers, remember?) so what they said was. Put them on the potty before bed. Wake them up 30 minutes after they have fallen asleep and have them sit on the potty. Then wake them again and have them sit right before you go to bed. I did this, and sometimes it worked, but mostly they were just very sleepy and so I'd have to "steady" them while they sat there, and they really didn't go much, if at all. I stopped that after a few days. Also, you'll want to limit liquids after supper. One other thing you can try is waking them up a bit early (maybe 30 minutes earlier than usual) and having them go then. I think I read most accidents happen right before they really wake up. As far as the sheets/bedding. I bought some very cheap moisture-proof mattress covers (less than $10 at Target). Bought 4, because we have two beds, so two for each bed. Then we also had two sets of sheets for each bed. Put one mattress cover on, then a set of sheets and then another mattress cover and the second set of sheets. That way, if there is an accident during the night, you just have to peel off the top layer of both sheets and cover, then she can go right back to sleep.
Good luck! And don't hesitate to contact me if you have any questions!