I joined my squadron on deployment and it was fine. Thing is, you get a dream sheet again to pick your coast and squadron. You really don't get a true say in what you'll end up with, Illusion of choice again. I'm very thankful I met them on deployment, learned a ton and got a head start on the upgrading process. We were lucky our deployment was a little more relaxed than it should have been.
Prioritize coast. That's honestly all you should care about. You will get your deployments in, don't worry about that. And upgrading will happen as fast or as slow as you want it to go.
Here's a little story for you about upgrading, I was ahead of the schedule, got all my PQS done for 2P, was ready for my board month 7 and didnt do it until month 11. Don't try to game it. Pick Coast you want, pick a squadron based off how cool their patch is and just let the Navy decide what you'll actually get.
Little edit: Would recommend joining a squadron about to head out the door or currently on deployment. I know I was vague in my post so I'll give you my honesty. This is what I think is best. You get your first deployment under your belt, learning a shit ton and you'll earn some salt. Also when it comes to picking your coast, try to go somewhere new. I've never been to the west coast and I wish I would have gone there.