Ideal cluster feeding would be separated by 2h so i.e. 4:30, 6:30 & 8:30 but some children may have 1,5h separation between two last feeds, some need 2,5h as they are not hungry before. The idea is to tank her up before bedtime so she doesn't wake in the first part of night sleep.
You also may try what's close to your current schedule so 6:45 and than 8. Or if you go to sleep at 9pm, you may wake up her 8:30 and settle with her at 9pm. Check what is working for her (she has to eat - sometimes when you offer breast to early they are just not hungry) and for you. It's not worth to do a cluster feed or dream feed after you went to bed, as the idea is to get more sleep for yourself:).