Early season, the trout are usually shallow and looking for staple food items like leeches, dragon/damsel nymphs, water boatmen and shrimp. Oxygen within the water is a bit better higher up in the water column because decomposition will decrease oxygen near the bottom. I love fly fishing with micro leeches early in the season. I have been tying most of my micro leeches using tungsten head turner beads that are slid onto a jig hook. Size 12-16 jig hooks are excellent to use for these small flies.
When you fish a micro leech tied on a jig hook using a tungsten head turner bead, use a clinch knot and you can present these tasty little morsels in a horizontal position under a strike indicator.
Glen's Leech, Ice Minnows and Bubba Gump Shrimp are always handy just after ice is off!