Without other usb devices the keyboard works immediately. With them it takes 5 ish seconds for it to start responding. This is regardless of which device is discovered first (which I can manipulate), it seems to just wait for all of them. Is there a way to make it not do that?
Yep if the MB has a PS/2 slot this is the solution.
You can also get a usb to PS/2 converter so you don’t need an extra keyboard.