The sentence seems strange. I think it should be “for” the whole day, but it still is a bit unnatural. Without any context, it seems to me the person is trying to say that his or her schedule is entirely full for the whole day.

There is definitely something wrong with the statement.

HI. that sentence is not correct..maybe,, This sentence seems meaning this " I have a schedule all day, so i have no extra time." thank you.