Manager life..

So I've been with the company over 3 years and have been promoted to assistant manager in September. Well a few months have gone by and I've tried to accommodate to peoples schedule but I feel they are starting to take advantage. We dont have a real policy in place in regards to calling out or taking off. Some weeks I will post the schedule and then they approach me , I need off Friday etc and it has become too much of a hassle. I sent this group text to all, and noone responded. I haven't been too much of a bitch but I feel like I need to start putting my foot down or they will walk all over me. Our front desk called out the passed 2 days and tomorrow is her off day for this week since I am accommodating to the other front desk needing off.

I dont want to write people up because that comes with a heavy consequence. At the rate they call out, they will all be fired in 6vmonths lol. So I was thinking if they call out on a Monday, the following day or week I give them an additional day off sort of as punishment for calling out , losing hours. Is this the right approach? I want to ask my manager for his thoughts but dont want to sound like a petty idiot. What would you all do ?