My roommate has not been living here for over three months. All of his crap is still in his room. He has never paid rent or any of that stuff and my name is first on the lease. How long does it have to be until I can throw out his things?

Is his name also on the lease, or was he sub-leasing from you? If both names are on the lease it makes absolutely no difference whose is listed first.

The standard procedure for dealing with "abandoned" property is to notify the person IN WRITING that you consider their property to be abandoned. The requirements for how long you must hold it, how many notices you give and what you do with it vary by state.

If you are his "landlord" you can go by your state's landlord / tenant laws. There's a "sticky" at the top of this forum with a link to each state's laws.

I should add that it doesn't matter how long he as been gone, the clock starts ticking when you notify him, unfortunately, not when he left.

Also, if you are jointly responsible for the lease and he bailed out you'd also have a good case against him in small claims court for his half of the rent and expenses that you've been paying.