First, make your command buttons a control array. So they become Command1(0), Command1(1), Command1(2) etc.

In your form's declaration section declare a variable to be used as a counter. Such as dim MyCounter as integer

Set your timer control for 5 seconds (5000 ms)

Your Command1(0) event should be to enable the timer.
In your timer event, have it increment the counter, then click the command button for that counter.

MyCounter=MyCounter+1
Command1(Mycounter)_Click
if MyCounter=4 then timer1.enabled=false

This should get you started.