I had a male that I didn't get neutered until he was older and he did start to spray.... mostly in my clean and dirty laundry. Neutering him was a night and day difference. He never sprayed anything again after that. I realize I'm the exception rather than the rule, but just wanted to say... it does help curb it, if not eliminate it. If they don't have the desire to want to spray, they won't.

Glad you're bringing him in to be neutered soon though!! It is the best you can do for him (besides giving him a loving home, of course).