Hi! How long do you let your bc crust before you use the impression mat on it? I am doing diamond imprint, which I've done before but it doesn't come out as sharp as I'd like and sometimes sticks. Any tips would be appreciated. TIA

How long to let it dry depends on the recipe used and the weather conditions where you are.
Get some tulle - bridal veil netting - and put it against the cake before using the impression mat.
Yes, it does keep from getting a really sharp impression, but then you can take a ruler or similar object to go over the lines. HTH