It's never too late to get to know your character. If you're having trouble writing, your time could be better spent catching up with these guys. That's why I say, I love it when I have writer's block, because it gives me an excuse to slack off, in a good way. One comical way to do this, is to put the characters in a group. I choose a plain room, with dim lights and a circle of chairs, with one chair for you.
Record what order everyone is sitting in and have everyone introduce themselves, starting with you. Think about what everyone's body language looks like, what they are feeling; thinking, and what they think of you. Ask yourself, who knows each other already, when is this taking place in respect to my novel, did some of them have to change their schedule to be here, and depending on the time it takes place, would meeting each other today somehow change their relationships and the outcomes that are featured in the book?