Many others who have completed will have a better view than me.
I started, after the early morning Eucharist and blessing, from Canterbury Cathedral in late August 2018 intending to at least achieve Reims. In the event I did another week beyond that. I prefer colder weather and this was too warm for me most days.
With my preference in mind I return early April 2020 to Langres.
This means I most likely cannot attain Grand Saint-Bernard as, mid April or so, I understand it will still have much snow on the ground. Will play that by ear when I get there.
For me that is a small price to pay for avoiding the warmest months in Italy.
Hope my preferences help with your thinking.
Kia kaha (take care, be strong, get going)