I’m not sure which route you plan to take but here is a link to the route I cycled with some friends on EveryTrail which takes your via Newhaven, Dieppe, Forges-les-Eaux, Pontoise and Paris. It was tracked using my iPhone so may not be 100% accurate, but it should get you there.
If you register for a free account with these guys you can login and download the .gpx file and send this to your GPS device.
I would say that the timings we’re pretty slow for us as this was our first long distance trip and a couple of us we’re cycling with injuries so you can possibly cut off a hour or so from each day.
Anyway I hope this is of some help to you.