Erm - that’s it really 
I expected that if I chose to ride (for example) Watopia Flat, I’d start at the start line - but I’m not sure that I am. It often seems as though I ride for a while, then pass the start - as the timer at the top of the screen kicks in. A real downer if you’ve already done a deal of miles & time that you thought were on the route.
Thanks.
Everyone starts well behind the finishing arch. It takes a little bit to get up to speed so that might be the reason why.
Yes, some routes only go under the main start arch at the beginning and it sometimes takes a little bit to get to the actual beginning of the route. You can use this time as a warmup period.
The timer at the top is not for every route, the Watopia Flat does not have its own timer.
There is a little learning curve to Zwift and you will master it quickly.
Ok, thanks Paul - and looking at a map (from https://zwiftinsider.com/wp-content/uploads/2017/03/Watopia.pdf) I realise that I’m starting at the green arrow to the left of point A below, and am then cycling towards A to start the course I’ve chosen. Which is pretty much what you said
Thank you.
Hi, thanks for the above link to map of Watopia:). Just what I have been looking for.
i tried to find the two other maps also, but didn’t find them - do you have the links?
thanks in advance.
Jan
After the update today there is at least one new starting point, at the entrance to the road to runs.
Jan: Zwiftinsider (https://zwiftinsider.com/) has all the maps route and much more. Happy reading.
Gerrie: so have I understood. However it is not so easy to find what one are looking for among all the stuff there 
But many thanks for the Zwift app. It is super - even for a 60+ old guy
This link should take you to the Maps. https://zwiftinsider.com/route-details/
These have not been updated:
The London map will be changing very soon.