For a primer, I like to use KRYLON and I have used Rust-Oleum also Tamiya. I have good luck with all these. I can find these at local hardware stores and Tamiya at Hobby Lobby. In my case, I go by how heavy a coat of primer I put on as to how much time I'm able to work on them. A lite coat can be worked on sooner than a heavy coat. Tbzep I have seen some of your rockets here and you do like sanding so you won't have any problems. I'm glad to see you get your hands on one of these rockets. I'm sure you will have plenty to say about build this 3D type project.

The white putty I use is Tamiya from Hobby Lobby. I also have used Squadron white putty but I have to order it.

I get good results from all these products. I like to let my primer and putty dry for a day or two before I start sanding.