I'm planning to sand the floorboards in our dining room this weekend
and would like to get my wife and baby out of the house while I'm doing
the sanding but have no idea how long it will take?

I've got everything prepared, room cleared, all boards screwed down
etc.

I want to sand the floorboards first to get rid of the top layer of
dirt etc and then sand a second time to collect the sawdust to fill the
gaps between the floorboards. I will mix this with some special glue
like liquid (which I'm getting from sanding shop) and allow to dry
overnight. I will then do the final sand on Sunday using 2/3 different
grade sandpapers.

The room is about 12 foot by 12 foot.

Obviously they only need to be out while the sanding is going on, not
while I'm filling the gaps.