You will hear the term "Christmas Exodus" the time when the base sees a lot shut down and soldiers on leave.
Can't say how it works for different BOLC's since I'm sure each runs their program a little different.
My older son went Aviation, since his training was a PCS move things worked a little different. A-BOLC was at the beginning, they basically trained during the day and then went home at night, either on base or off base housing. They had most weekends off and the time was their's, though thy did have distance restrictions and needed to obtain a pass to travel overnight within that distance, I don't think they were ever denied the pass. Once A-BOLC was over they continued on with training and flight school, he was allowed to take a week over Christmas to come home.
Aviation BOLC and flight school is a whole different process then other BOLC's, I know Infantry is a long period as well considering most head straight to Ranger School when they are done.
Hopefully Norwich Dad will see this post, his son went through IBOLC and he may be able to give you much more information, you might want to send him a PM and ask how it worked for his son.