mrbb

I too would question if its even legal to add concrete to a wetland)swamp)
I know in my area its highly illegal

BUT there is NO set answer as to how long it takes deer to get used to something new
an example will be this,

I have plowed roads and opened sections of forested land with a bulldozer and had deer in them while dozing, and have done the same thing in another place and deer seemed to avoid the new openings for weeks

I have poured concrete in some residential neighborhoods, doing driveways and had deer walk in the wet cement before it dried
A deer is an individual critter and they all think and react to new things differently!
how well adjusted they are to humans or not, can matter

SO< there is NO exact answer for your question!
best answer is
it will take them as long as THEY need to feel comfortable with the new changes to there home range!