How Long Before Mask Must Be Removed

I have a question regarding the length of time a mask can be applied without damage to the canopy. I need to mask a 1/48 Accurate Miniatures B-25 C/D with Black Magic Mask.

Me, like most of you have a limited amount of time to devote to our hobby. The time frame for me to mask, prime, touch-up, prime again, paint, future, decal, future, weather, and final flat could be 4 weeks or more. In the past, I have applied the mask, did the priming and touch-up, primed again, and removed the mask. I would later, reapply new mask and paint. In one situation, I masked the same model 3 different times - WHAT A TIME WASTER!

Question #1: Just how long can you safely leave these mask on? Same goes with the Eduard brand mask as well as Black Magic.

Question #2: Should you future the canopy prior to masking or after? I seem to remember someone recommending that future not be applied until after the mask are removed. But, I may be dreaming.

I Just pulled the mask off my Cobra canopy. its been on there about 4 or 5 weeks. without future under the mask (i future over to seal the edges) And it came off clean. Just starting to get some fogging a few days later. Are these proper masks or masking tape? Ive used tamiya masking tape for mine.

Proper mask purchased from Black Magic and Eduard.