Well, at least you're close to an airport!! I would imagine that you would want to use TF Green. What I do is to decide on an airfare that I can live with...for flights to Orlando, I usually like to stay below $200 pp for a direct flight from either TF Green or Logan. Once I decide that, I just keep checking to see what the airfares are...every day. When I find one that suits my budget and has good times for me, I book it. I can't obsess over $10 here, or $10 there. I'm paying a ton of money to go to WDW...what's an addtl $50 in airfare for the family.
I have had good luck booking as far out as possible. But, Delta will make many changes before you fly when you book way in the future. At least SW doesn't change their schedule around. I would go with SW and book as soon as you see a good fare. I just booked Delta in mid-Oct for about $170 pp, but it has already changed times once.