How early to rent car and book hotels in Alaska for July 2015?

We are a very very large group(19 and growing families) and many of us plan to split in groups and do our own land tours but, most of the families plan to rent their own car and try to stay at the same hotel as everyone. So, how early can one book without running into problem of "not available"? Don't want to book too early and get money stucked either.

I am guessing Oct, 2014 would be right time to do after booking the flights or is that too early/late?

For the past several years Enterprise has run great deals from their International Dr office ... I start watching their site in mid June for a deal for the following year. Sometimes it starts in June but sometimes its July or August. You just need to be diligent and check the site frequently. You can get an economy car for $125 a week so its worth the effort!

Check all the sites.