How early can one check luggage for a flight?

I ask this because I'm contemplating arranging flights for a vacation that would have me flying in from one place and transferring to another much later flight on another airline. For example, if I were to arrive 12 hours early for my next flight, is it possible to retrieve by bags from my first flight, check them in with the next flight then leave the airport for dinner/sight seeing/whatever and return later for my second flight?

Depends on where and what airline. I know some airlines limit domestic luggage check-in to 4 hours before departure. And many international airlines don't open their check-in counters until 3 hours before departure.

Agree, and with security issues these days, most airlines won't do that. Best bet is to try and find a storage facility at the airport.

O.k., here's more info.

My plan is to go to Hawaii. While reviewing airlne schedules and fares, it seems less expensive to me at this time to fly to and from Honolulu on a carrier from my midwest city and use a speparate flight on Hawaiian or Aloha for an interisland transfer.

If storage is available at HNL, then great. That's what I'll do. What I'd rather not do is keep the luggage with us. Therefore, handing it over to the airline for the return flight would be the best. Storage second. If that's even available. Least preferred is keeping it with me.

I think you're asking mainly for your return flight. Aloha, Hawaiian or Mesa should be able to check your bags through to your home airport, as long as it's same day transit. Even if you buy the tickets separately.

Yes. The return flight.

As you've noted, I'm planning on making two separate reservations. One with an airline like NWA or Continental. For example. Then Hawaiian or Aloha. That's because of what I noticed when I'm looking at airfares.

So what you're saying is that even though it's not 1 ticket and each airline really doesn't know what I'm doing, when my family and I show up in Kona to begin returning home, at that time, I can have Hawaiian or Aloha check our bags through? BTW, this will infact be the same day. Leave KOA in the afternoon, go to HNL, then return to the mainland.

When you check in with Hawaiian or Aloha at KOA, show the agent your HNL-mainland ticket and ask that your luggage be checked to your final destination.

Yes, that can be done, as Hawaiian and Aloha must have interline baggage agreement with NW or CO. Just tell the check-in agent at Kona about your connecting flight. They will confirm it, and then tag it to your home airport.

Great. Thanks for the advise. Doing so will take care of the "what to do with the luggage" question.