It depends a lot on your company, so I think your inside view will be better than our outside view. I told my employer when I went out to do a tryout with CFAR, and that went well. One reason I told my boss was that, if I were hired, I'd need to scramble to get all my projects annotated well enough to be able to pass of seamlessly, and I didn't want her to be left in the lurch or to make any plans that hinged on having her quant around for the next month. (Hiring sometimes took a while at my old company).

My boss really appreciated my being forthright and it saved me a lot of tsuris. I think it also worked better because it was expected that people in my role (Research Associate) wouldn't stick around forever.