Love at first sight is totally possible. Especially since love isn't even quantifiable or describable really. Its just a feeling. I'm not really a sucka for love but I def can wear my feeling on my sleeve when it comes to a person I'm digging tough.
This is one of the main problems I have with many gay men, especially the more masculine types. They often play hard to get or act like they need long periods of time to decide that they even like a guy, let alone love him. If you need weeks or months to determine that you dig me, I'm not the one for you.