I have two Gralab 300 model timers in my 6' x 12' darkroom, and I asked this same question. When I could get no answers, I did the following test:
I placed the Gralab at the foot of an 8x10 film holder loaded with Bergger BPF 200. I set the timer for 1 minute and pulled the darkslide half way out, revealing 5" of film. The luminous dial was within 2 inches of the film for one minute. After 60 sec. I turned the Gralab around, pulled the darkslide the rest of the way out and put my luminous dial watch directly on the film surface for 30 sec. and then, in a different spot, 6" away from the film for 30 sec. I then developed the film in HC110 at my N+2 time/temp.
There was NO evidence of the Gralab or the watch dial held above the film. There was a Zone V round splotch where the watch had contacted the film.
Conclusion: Don't take off your watch when loading film. Don't worry about the Gralab fogging film. Don't lay a luminous dial watch on top of unexposed film.
DE