I do 45 minute acclimatisation for the more expensive and delicate species, I empty the contents into a jug, then I take some air ling and tie a knot in it so it limits the flow, then I start a siphon from the tank allowing 2-3 drips a second, as the jug fills up you can empty it into the bucket, but don't be too rough with the shrimp.
for the hardier species like cherries I just do 15 minute acclimatization in the same way but allowing more drips.