Excel Timer function

Good day,

In cell A1 we have the word "one", and in B1 we have the word "two". Would it be possible to have a timer function run for 5 seconds, counting from 5 to 0, and everytime the timer reaches 0, the word in A1 is copied and pasted into cell C1, the timer resets and counts again to zero, this time when it gets to zero, it copies and pastes the word in cell B1 to C1. So it's like a flip flop function, with cell C1 changing it's value every 5 seconds. Also, this code needs to start running automatically when the sheet is opened. Is this at all possible with VBA?..

Thanx for the help!!