Hey! This one is also my first game and game Jam. I recomend you to try working on something small, something in which you can progress fast. Not too much mecanics, not too much ambition. Just, something cool and funny for your first game. Altough, It can be funny or not, it doesn't matter, the important thing here is to learn. Good luck dude. :D

I can only speak for myself, but I do procrastinate a looooot... so... in my experience you have to find the reason for it. For me it's fear, overwhelmedness in front of all the tasks I have to do. Not knowing where to begin and where to end.

So my tip is:

Make a plan! A realistic plan. List all the things (yeah all of them, so you know excactly where you stand) you want to do and what progress you made with them. Cross the things you did from the list, it will give you a  sense of achievement and retain a positive attitude (aka motivation). If your stuck on one item of your task list, leave it for now and make something else. Finish small part - goals.

Maybe download some project management software. It helps to have an overview rather than shooting into the blue. Not knowing if you're ever gonna get anywhere. I use the app "Project manager" because it's simple and fast and doesn't steal me more time than it gives. I'm addicted to crossing out things from that list now.

PS: I was procrastinating as I wrote this. But not with my game, but with my master thesis, lol...