This won't help, but anyway...
I checked all three books I have on alt methods. For traditional cyanotypes, there's nothing to say how far in advance you can coat the paper, but all seem to suggest using it as soon as it's dry. For the 'new' (Mike Ware) method, one book says to expose within a few hours of coating. Another says you can leave it for days but does say the result won't be the same (they seem to be suggesting the result may be better).
My own personal experience is limited. I've only used the new method and I always coated the paper immediately prior to using. I think the main thing is consistency which you won't get if you coat paper and leave it for varying amounts of time. That might lead to frustration. It took me a while to get the process down so I was getting consistent results.
My suggestion would be to coat paper immediately prior to using but, maybe, keep a couple of sheets and use them later to see if there's any variation in result. Someone else may know better.