late entry

I have a question: Is it ok to write "late entry" in the nurses notes?

Agreed, but there may be rules or even state laws governing how it is done. In my facility, under 24 hours the chart MIGHT be still on the floor and accessible to the nurse. Once it leaves the floor, or once 24 hours has transpired, the nurse must get permission from Risk Management. I think the idea is that lawyers get suspicious if you have a day or two to think about what you WISHED you had written. Best to ask your supervisor or check the policies for your facility. Or both.