I used to have a book on the specifics, but I donated it to the library (with a lot of others) when I moved. From what I recall, though, an attendant's costume was based on what he was doing and where he was, rather than what the time of day was. The outfit usually sported by Stephen Fry (when he was in tails, in Bertie's flat) was this one http://en.wikipedia.org/wiki/Morning_dress (though with a bowler/derby hat, rather than the top hat) and as for the books themselves I am unfortunately not currently near my collection to look up any reference from the source material.

So it depends if you are showing book Jeeves (whose clothes, if I recall, were not frequently mentioned) or Stephen Fry Jeeves, indoor or outdoor.

I can hunt down the name of the book, though, if you're interested.