Creating proxies in a production after the clips have already been used in other projects

Hello!

I am working for the first time in a premiere production and the playback is starting to slow down in my timelines. I have a project within the production with my footage and other projects with timelines that are referencing the media already.

This is not the ideal situation as I naively thought I could get away without making proxies initally as the footage is only 1080p (also h.264, I am now learning a valuable lesson that h.264 is not a good codec for editing) but if I were to create proxies through premiere in the project containing my media, will this propogate through to the other timeline projects and I will be able to use the proxies there?

On the premiere pro best practices pdf, I could only find information for this kind of situation where it says on page 42, "If you are working in a Production, create your proxy media before starting to edit with those clips." I didn't want to mess with my production in any way by going ahead and making proxies considering it says this, but I think as the production gets bigger the playback issues will get worse so I'd like to do something now if I can. 

Any advice would be greatly appreciated!