The nursery is the one that always decides when you take your lunch break.
It can be somewhere in the middle of your shift, but it can never be at the beginning of your shift or at the very end of your shift. The minimum time they have to give you is 20 minutes, but if you work for less than six hours or six hours exactly, you are not entitled to a break.
Please always either ask the nursery manager or room leader, what time can you take your lunch break or they will come to you and let you know. But they are the ones who need to decide as they have to count the numbers and everybody is working in shifts.