They usually appear mid april to June Best bet if you haven't fished them before is to travel up to the Lawrence Dam and points south and watch other fishermen,ask questions.Other favorite location is Rocks Village south of Groveland. DeGloria's sport shop off of 495 on 110 has darts and willow spoons and usually good info on where to go.Shad also can be located in lowell behind the ballpark in early june,but finding a legal place to park can be next to impossible.My go to darts are pink/purple,gold/red,red/chart.Willow spoon#2 gold/red and gold/chart. A small(1/16) crappie jig red or chart. colors can also be productive at times.I've even used a #2 gold bait hook with a colored bead pegged at the knot ahead of the hook and had success.
Good Luck - Good Fishing