You can go ahead and harvest those crystals, if you're feeling rushed. As long as there's more remaining in the naptha, the naptha will pull less next time you put it in. This means that your looking at doing more pulls if you're not crashing out a significant portion of the contents in your freeze precipitation. What I would suggest here, if you're really in a hurry, is to filter the naptha into another jar, and put that in the freezer for the four more hours, and let the spice dry out with a fan over it.
When SWIM is doing her pulls, as soon as she removes a pull, she puts in the solvent for the next pull.
PK Dick is to LSD as HP Lovecraft is to Mushrooms