Hey Jimbo, welcome.

It probably is better if you write down your dreams immediately upon waking up in the middle of the night. The benefit is that the dream should still be quite clear in your mind and will most likely fade as the night continues. That being said, you don't have to. Like you, I just write down my dreams when I wake up in the morning, and this suits me fine. My recall is generally pretty good.

I was also similar to you starting out in that my dreams didn't seem out of the ordinary. If you keep at it I'm sure you'll soon get some unusual dreams that contain interesting dreamsigns. Your dreamsigns might also simply be the ordinary things you currently are dreaming about. My advice is just to keep on recording and see what happens.

Hope that helped, enjoy it here