The scale seems good but it may be hard to fit geckos on the platform. I use this one Amazon.com: American Weigh Scales Black Blade Digital Pocket Scale, BL-1KG-BLK 1000 by 0.1 G: Kitchen & Dining and it is hard to fit some of my adults in it.
From my experience it takes around 45 days at 84.5 degrees for them to hatch. Not sure about the other temps but a general rule is that the hotter the temps the shorter the incubation time!