There will be midgies, some parts will be worse than others. Get something like
https://www.ebay.co.uk/p/?iid=222449386 ... t=0&chn=ps for when they become unbearable
It's always busy on the WHW but the main wave of people seem to start on a Saturday & walk over 7 days. I spent a week in Tyndrum last month & every night there were WHW walkers in the pub, it was never overly busy apart from the Tuesday night when it was standing room only & an hours wait for food. This was the 7 day Saturday starters. If you start on a Thursday, you'll be ahead of the masses.
You haven't said how long you're doing the way, but on most sections, there will be a pub/café/hotel that you pass where you can fill a water bottle.
Definitely take the path over Conic Hill & take the small detour to the top for the view down the loch.
Other tips, take your time, enjoy the scenery & the great camaraderie along the way. Too many people try to rush along with the sole focus on finishing. It's a great walk, enjoy yourself.
Oh, & make sure you visit the Drovers at Inverarnan & also the Mountain Café at Glencoe ski centre (amazing coffee & homebakes)