The ideal practice is to leave the foliage intact and in place until it ripens, dries and dies off naturally. The foliage is needed for photosynthesis, which is required for the bulbs to regenerate their energy reserves that are stored in the bulbs during their dormant period and produce next season's flowers.

Ripening bulb foliage is not very attractive and there is a strong urge to remove it as soon as it becomes ratty looking :-) But the bulbs need it. Generally, 6-8 weeks after bloom is considered the minimum period necessary for the remaining foliage to do its job, so try not to cut back or remove before this time has lapsed.

Pat -- if you have space, grow daylilies near your daffs -- they allow daff foliage to ripen naturally and then cover up the really unsightly yellow-brown daff leaves. as the daylily clumps get bigger, you can divide them so that they don't over-grow the daffs completely (gettting free plants to boot!). i never cut my daff foliage and remove it only when thoroughly brown. gotta feed those bulbs, ya know!