Take current date issue in Excel

I have two columns A1 and A2 What I want to do is for A1 to take the current date mm/dd/yyyy if A2 has a value bigger than zero (0).

For this I used the following formula in A1

=IF(E2>0;(TODAY()))

So if a cell in A2 is for example 60 then A1 will be 11/03/2015 If I save this and reopen it the next day the values in A1 will automatically change into the new date. This is something that I don't like as I want to use this method to keep track of my expenses each day. So if I type an amount in A2 I want A1 to give me the current date and keep it.

So how can I get the current date without worrying that every time I reopen the file they will change.