I just free hand sharpen with a 4 1/2” angle grinder fitted with a 40 grit flapper. Follow the original angle.
Cut you some 2x4s or 4x4s. Cut 2 at 3 1/2” long and 2 at 3 5/8” long. Set your height selector pin to 3 1/2”. The outside blades should be facing front to rear. Slide the 3 1/2” block under the front facing blade tip and 3 5/8” block under the rear facing blade tip. These blocks should just slide under the blade tips.
Number of turns? That really doesn’t matter. Turn the bolts CW or CCW until the blocks slide under the blade tips.
Best time to cut? It depends. You certainly don’t want to cut if the grass is soaking wet.