Tim,
Sorry for the delay in replying (kids + gardening = no spare time this weekend!)
Holm (
www.ww2.dk) has the following locations for JG1 in Msrch '44:
Stab. - Rheine
I. - Twente, Hopsten, Wiesbaden-Erbenheim
II. - Rheine, Wiesbaden-Erbenheim
III. - Mönchen-Gladbach
20. - Wittmund
I'm, unfortunately, way out of my comfort zone of late-war ground-attack units now, so perhaps someone else knows the precise movements of JG1 in your timeframe,
Cheers,
Chris