Vehicle V5 just received not insured?

Hello, I've only just received the V5 for the vehicle I purchased about 2 weeks ago this weekend. It is currently uninsured. I know you have to declare it, but how much grace to they give you? will I receive a letter then have to declare it SORN? Because my test is next Tuesday and just in-case I did p I would want the vehicle with tax, as we re-taxed it when we bought it. I would SORN it if I didn't p on Tuesday obviously so is it alright to do this? All I have is the V5 I have received no letter about Insurance etc or how long you get to declare it SORN? Help me