Don't wait for the milestone start
I'll start it on Monday.I'll write everyday starting next year. I'll start the project on the 1st of the month.
I'm guilty of employing this delay tactic a million times.
But, despite its rational roots, that is all that it is: a delay tactic. A way to feel good about your ambitions while procrastinating and not taking any action.
Your future self will thank you.