2018 Tour De France - schedule with start times?
The Official Tour de France website has this information. Alas, it's unlinkable but:


Select "Route 2018" from the top menu bar.
Click the stage you're interested in.
Scroll down to just above the map, where you see "Sport Side"*.
Click "Time schedule".


Times are given in local time, which is CEST (GMT+2).



* The TdF website has always had somewhat idiosyncratic English. I don't know why they don't just get a native speaker to write their English content.