If time is not a factor, then I would let the price decide.
If you can get a better price by having the work done in the off season and you are willing to gamble that the weather may delay the job after it starts, then do it in February.
If the price remains the same and time is not a factor, you may get a better job in warmer weather when the crew installing the fence won't be rushing to get out of the cold.
Also, because of the frost, the depth of the holes may not be consistant.
Just a thought!
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