You might as well jailbreak now. You can install tweaks, but they just probably won't work. They'll probably mostly either be updated within the next week, or they're abandonware and will never work on iPhone 5S, iPad Air, and iPad Retina Mini. I've jailbroken my iPad Retina Mini (also ARM64) and a quite a few tweaks already work, e.g. Activator. Just don't try adding themes yet.
Also be aware that once Apple puts out a new OS version, you will no longer be able to go back to 7.0.4, and thus you will no longer be able to jailbreak (until a new version is released, if a new version is ever released for 7.x). I haven't done Winterboard Themeing since 4.x due to this--at least historically, if you had a lot of different themes and tweaks installed they could really make the phone unstable as hell and require a restore to fix. Maybe it's better now. I've never had a problem with phone instability beyond theme installations, but almost the only things I use now are tweaks to speed up the phone (ugh, the animations are so slow) and Activator.