In reply to bendavidsteel:
The whole GR54 takes at least a week for most in summer using guarded huts, gites etc, most of which will be winter room only at the moment (even in the valleys many businesses such as cafés & hotels are shut). Much of the higher ground is snow covered at the moment although unlikely to be consolidated so might be slow walking. There's a user called Badmarmot (or similar) who lives near Vallouise who might give you better information for that part of the Ecrins but its not that far from here as the crow flies & doubt conditions are very different.
Have you checked the weather forecast? seems snowy & cold for much of next week