Putting up fencing? Too wet?

smashed

We have recently removed some trees / hedges, and then flattened the garden. We planned to put the fencing up but the weather has recently been horrendous leaving the garden (Which is now mud) boggy. We have covered over where we plan to fence to reduce how wet it gets but wonder if it is possible to still put the fencing up on a dry day?
Can anybody please advise whether this is feasible or if we are asking for problems? I am hoping that it will be ok 2 foot down and that it wont result in the fenceposts moving before the fences go in 2 days later.

Thanks