I can give you heaps of tips Ken, I'd say for your first don't worry about the shoes already clipped in as invariably you'll lose time for faffing getting the pedal to spin back round and wobble like hell as you bend to fasten the strap regardless of the velcro!
Have you done an OW swim yet? it will be cold and dark but don't worry, I know tips for that too. I had a proper proper fear of Open Water and if I can swim 2 and a half miles in the sea then you can do it in a lake, mind you the South of France was a lot warmer!!
At least on leg 4 you can take my mind well and truly off Yewbarrow if you ask me all about the tri's then, I can waffle on for hours!