I am purchasing my first home, my boyfriend and I will live there. I would like him to sign a quit claim deed, because I do not want him to be able to claim any rights to my property. Can I my boyfriend sign a quit claim deed before we get married? Would it be valid?

Yes, but for what purpose? He won't show in the title in any event, and until you are married he will have no claim to it.

Consider a prenuptual agreement.

A Quit Claim deed is used to transfer interest in a property from someone who has a current interest in the property to someone else.

Since he is not on the title now, there is nothing for him to quit claim to. As AK said, if you don't want him to have any interest in the property, you need to prepare a pre-nup or cohabitation agreement.