I would say you are a wee bit early but based on previous trips in late May I would recommend the following.
Loch Craggie
You are a wee bit early for the Mayfly but I would still recommend the following patterns fished on a floating or intermediate line.
Wet Daddy with yellow seals fur body, Red Ar5e Green Peter, Hedgehogs in Claret & Olive, Doobry, Black Ke-He, Dabblers in Claret & Olive, White Hackled Invicta
Drifts along the shallow margins on North and South banks should produce fish.
Loch Eye
Again a wee bit early for this long as May can be a windy month with cold east winds which can put them down. Drifts at the western end know as the "Monks" should produce fish, unless it warms up cortland camo or fast glass would be my first choice.
Fly patterns would include; Hutchs Pennel, Peach Muddler, Jungle Cock Bibio, Jungle Cock Kate MacLaren, Connemera Black, Mallard and Claret and would highly recommend you fish a craftye devil. These three fish all caught by seperate anglers were all caught on the Craftye at the end of may last year fished on the point on a cortland camo line.
I couple of my mates are on there on Sat so I will drop you a pm on Sunday to let you know how they got on.
Cheers
Gerry