Howdy, gents. Gurunet has:
a·non (ə-nŏn')
adv.

1. At another time; later.
2. In a short time; soon.
3. Archaic. At once; forthwith.
idiom:
ever (or now) and anon

Time after time; now and then.

[Middle English, at once, from Old English on ân : on, in; see on + ân, one.]