Do Apply Early
Like others said, be honest. Give them your best guess at availability. Accept any and all offers up to the time you HAVE to make a decision. A bird in the hand is definitely worth two in the bush in this case. We had guys in my new hire class leave to go to another carrier during indoc. Yes, they burned a bridge, but went where they really wanted to be. For most guys leaving the military, it is a hard concept to grasp that you don't owe the new company anything. Remember, they will furlough you the day after hiring if it suits them. It's business. It's also business for you. You have to make the best decision for you and your family. If it means telling a company no after you told them yes, then so be it. It's business. If you dump one company for another, they may not necessarily like it, but they won't cry over it either. They will just move on to the next guy who will be elated that you bailed and gave him/her a shot. They will not take you back after that point though, so make sure you are leaving them for good. On a side note, I took the first training date available and ended up at my last choice airline. Turned out it was a blessing in disguise. Like Garth Brooks said, "Thank God for unanswered prayers." Sometimes its for the better. Good luck. Multiple choices and decisions is a good problem to have.