They are very inpatient some check their farms almost everyday. With their presence how can the birds find peace. Can't really blame them this is human nature, curiosity. They want to find out how many patches of bird shit in it, whether the birds had stayed or otherwise and whether the equipments installed are functioning properly and so on.
I would advise that after the farm completed a check list should be done making sure all equipments, all alterations and whatever needed to be put into the farm are completed and at its final before the sound is played.
This would prevent frequent entry.If there are still uncompleted task and once the sound is played especially for new farms, there would be birds playing outside the entrance hole and some birds may try to enter the farm. Imagine birds entering the farm and you still have unfinished task in the farm this may frighten the birds.
To find out whether birds had stayed all you need to do is to check it from outside. Its more accurate than checking from inside.
At 7.15 to 7.45 pm depends on areas, look at the entrance hole it will tell you how many birds actually stay in your farm for that night. Most birds that enter the farm at that hour will stay. For new good farms 100 or more birds will enter within minutes. From here you would know how many birds had chosen your farm.
(glide down with speed to enter farm)
So you may try it this evening to find out how many birds actually stay in your new farm.