It suggests at least 4 to 6 inches of black ice for ice fishing/walking on the ice. It offers other important safety information that's worth reading, even as a refresher.
http://www.wildlife.state.nh.us/Fish...ety_on_ice.pdf
Personally, I wait for at least 6 inches measured off Cattle Landing before heading out to Mink and I ALWAYS test the ice along the way the first trip out. Ice thickness can vary by several inches over that 2 mile trek. Carry ice awls -- they could save your life.
Please be especially careful heading out at night or blazing the first tracks over unfamiliar areas this time of year. For example, I've hiked out to Mink in the past only to find the ice between Mink and Jolly to be at best 2-3" thick (vs. 7"+ elsewhere on my hike out) - passing snowmobiles were literally creating wave action on the ice. I remember thinking they were taking far greater risk than they realized. Sadly, hardly a year goes by that someone doesn't die in the Lakes Region from a mishap on the ice.
Given the forecast, we should have a very solid base (>12 inches) by mid January -- Nice!