we have a process that runs automatically based on a daily timer we are us

This is standard behavior. What I have done to avoid this is to place a decision node at the very beginning of the process - toggle a Boolean constant to false when you are working on the model, use this in the decision node to decide whether to continue on the normal process flow or to End directly. Once the model is published, flip the constant back to true so the normal flow will be executed at the desired run time. Alternatively, in the decision node you can always check that the run time is within a minute or so of the target run time - if not, flow to an end event.

Thanks csteward , i didnt know that this is a standard behaviour

No problem. I'm not too fond of it either, it would be much more convenient if you could perhaps check a box to not run the model on the initial publish - but this has been the way it has always worked.

You could check the show advance options check box that is present in the set-up tab of timer.Using the new expression,validate if the current time is 5:00 AM(your scheduled time).This would not create a new instance until the expression results true