Per the CO, DH gets one weekend a month during the school year. It is set that it is the long weekend for that given month. If there is no long weekend then DH and BM try to agree on a weekend. (This has been a huge failure every year so far)
This month starts school. SS's are back at BM's since practices started and they have to attend. There is only one weekend that DH can take after school starts because the next weekend is labor day weekend and it's BM's year. Any weekends before that are still considered "summer" weekends.
DH sends BM a calendar before every school year listing his weekends for the school year (this is based off school calendars). He sent this calendar to BM 3 weeks ago.
BM replied to him last night denying him the weekend in August. DH responded that he would just take the first weekend in September instead to count toward his August weekend but that would also give him two weekends in September but not much choice since there is no other weekend for him to choose in August. BM replied to him this morning saying that she will let him know if that will work.
Obviously, I can't predict the future and say what BM will say but if her past record holds true, and it usually does, she will wait until the week before that weekend and tell DH that she already has plans.
She is denying the August weekend because a little less than a week before DH was scheduled to bring SS's back to BM's she requested they be brought back 2 days early for some family event she had planned. DH had already made plans for that day but told her he would bring them back the next day (1 day early) which he did. She said because he refused to bring them back she rescheduled it for that weekend.
If this is already starting now, it will not be a good school year for DH's parenting time.