Scan the credit card offer letter very carefully. Usually the associated frequent flyer number is imprinted on there somewhere. If not, call Delta up and ask them. Miles dumped into your account are generally good indefinitely as long as you show some account activity every so often (one year to three years).

You need to strategize in one particular program or alliance, though. If you end up with 100,000 points/miles each in AA, DL and HHonors, it doesn't really do you any good even though you have a mess of total points.

I would gently point out that if it were usually feasible within 12 to 15 months to accumulate and redeem enough FF points to fly five people to Europe free at the height of the summer rush, everybody'd be doing it.

Unless you are a serious (100k+) frequent flyer, the kind of trip you're talking about takes years to plan and execute. Note that people start angling for the few seats available 331 days before the departure date -- which means that June 2007 seats start getting snapped up in July 2006, or just five months from now. And actually snagging five award seats on any transatlantic flight in summer would be a sort of religious miracle.

Given your accumulation rate and flying habits I would recommend:

** Deferring the trip until 2010 or so, or

** Trying for just one or two award seats out of five, or

** Forgetting about frequent-flyer awards and concentrating on hotel points instead; you could probably earn enough Starwood or HHonors points in a year to score some free lodging in Italy, and hotels in Europe in summer are pretty expensive.

Good luck!