Granted my experience in Colorado is probably pretty different than those in other areas, but I got my system turned on at the beginning of May. Looks great this time of year - tons of production, and almost no AC usage.
The one big tip I'll give is to at least consider a cash purchase rather than a loan if it's at all something you could make work. For my install, the loan price was $29k vs. $21k for the purchase (and you get 30% back from the feds on either). It's obviously nice to just have the low payments for ~25 years (or however your installer sets it up), but man...~40% origination fees is nuts. We managed to move some things around to make it do-able, but even if you plan to pay it off in a few years (rather than a long-term loan), a personal loan or HELOC will probably work out in your favor.
If by any chance anyone's interested in Blue Raven Solar (which is one of the larger companies out there), hit me up. They do referral credits that'll save you $500 and save me $500 as well.
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For context, mine is a 5.67 KW system, so it's on the small side. It only covers ~80% of our costs, but unfortunately I don't have enough south-facing roof to do much more than that.