It’s hard to time since you’ll be using a short light schedule. All the other growers are doing 18+ hours and can tell you it takes 6 weeks to have 4 plants outgrow a 3x3 (or whatever). But if you want to do 14 hours from the get go, it takes longer, and pretty hard to get advice since not very many people are doing low hours in a tent.
I’ve had friends get their outdoor grows ripped off and restarted in July and still had decent grows. And I’ve done multiple clones from topping months old plants that caught up to the mom. So unless you’re trying to grow trees, getting out early isn’t really the bees knees. You can easily grow a 6’ by starting today.
Granted I live in a very mild climate with no frost and doesn’t start raining till October.