You should still soak fresh frozen. It can get very brittle when frozen just like dry. Green can result from shredding leaf while too frozen/brittle. Some varieties also have leaves that shred easier no matter what. (Not good IWE plants)
When to grate is a key part of creating true Ice Wax. Ideal drying temp., grating temp., and timing will vary with each trim batch(grow)/hash run and also by variety (resin profile). IME the meltier varieties need to be cooler to even grate.
Drying should be slowed by BOTH cool temp and proper humidity. The idea is to initially "dry" it cool and at the correct humidity (thus rate) to the perfect grating point, but grate it before its "completely dry" and traps water/moisture in at the microscopic level. (This is what makes most bubble hash bubble so much, trapped water finally escaping! and IMO is a sign of IWE that could have been made better, not a sign of dankness!) Increasing the surface area before it heats up and the oils and water can more easily mix is what I am currently working on. The season is against me now though... Can't wait to move further north!