NO NO NO NO NO.

YOU CANNOT.

TRUST ME.

I just bought a 240z not that long ago and on the way home with it, just three hours after I bought it, I got a ticket for no insurance. Because I did not have insurance on the car, I'm now looking at A STATE LAW MANDATED 60 DAY LISCENSE SUSPENSION. You CANNOT get out of it by making a deal with the solicitor to plead guilty either. You do NOT want to mess with this crap, it's a headache I wouldn't wish on people I hate. Call your insurance company and get insurance on it. Even if you can't get proof of insurance (Which you should wait for) at least if you call and get the policy or add it to an existing policy before you get the ticket you can get out of it with just a $25 fine.

As far as the registration is concerned, you have 30 days, but you can go and get it done the same day you buy the car typically if you have insurance and the bill of sale, so there's no real reason not to get it done.

Just to reiterate: YOU MUST HAVE INSURANCE ON A CAR THE MINUTE YOU DECIDE TO DRIVE IT, REGARDLESS OF WHEN YOU BOUGHT IT. THE MYTH THAT YOU HAVE TWO WEEKS, 30 DAYS, WHATEVER, IS JUST A MYTH. YOU MUST HAVE ACTUAL INSURANCE COVERAGE ON THE CAR OR YOU WILL FACE A 60 DAY SUSPENSION OF YOUR LISCENSE.