+1 on double checking theres lube in there. the IGUS bushings are self-lubricating, but a little bit of grease does make them smoother.
to the original question, mine took about 2 weeks, maybe around 150 miles, before they really set in. just set your rebound to feel right (I only had like 1 click from full open at first) and remember to keep checking it for a little while. It'll get smooth eventually.