In reply to beer belly:
if you're arriving in milngavie at lunchtime you could just start the WHW then and walk straight to Drymen, it's only 12 miles on good terrain. You'd be able to get a lot further along the WHW, but you wouldn't be able to use Drymen 2 nights in a row. Depends on your aims and whether accommodation is booked already.
I don't know anything about your aims and level of fitness, but if I wanted a leisurely 2-3 days on the WHW from Milngavie I'd do the following:
- Day 1 arrive Milngavie at lunchtime, walk to Drymen 12 miles
- Day 2 walk from Drymen to Rowardennan 15 miles
- Day 3 Rowardennan to Inverarnan 14 miles then hop on the citylink to Glasgow and head back home from there
OR
-Day 3 up Ben Lomond, water taxi from Rowardennan to west side of loch and hop on the citylink to glasgow