Not for at least a year. The 350 will initially be a separate fleet until some sort of mixed fleet flying starts to take place.
The ex 330/340 guys will have a shorter 350 conversion course compared to the ex Boeing guys.
But the spare crew from mid 2015 are most likely to be on the Jumbo. So my guess is that the 350 will initially be crewed by a handful of trainers. This will be followed by a mix of line guys from fleets "A" and "B".