It’s going to be so great!
Just remember you don’t have to push yourself right to that edge so you go over by accident, even a ‘soft edge’ where you play then stop will do. You really don’t want to ruin too many orgasms or they’ll start to make you feel like shit. So just play safe, and be a good girl and DON’T CUM.
You’ll be so proud of yourself on Christmas Day and it’ll feel so good!