Is it okay for your period to come early?

My period was supposed to come, according to both flo and glow, Monday, but today is Thursday and I just woke up and had to change my panties because of it. I wasn't expecting my period today, so I was a little thrown off. My periods are usually on time or late, so. I mean I'm glad I got it, because the past couple of months it's been late. Is this okay to happen?