Overview:
A form has a property called ".Timer" which is milliseconds.
When you set the timer to a positive integer, Access ticks it down until it goes zero. At any time, you can read the timer to see what time is left.
The Form_OnTimer event fires when the timer ticks down to zero. It never goes negative on its own.
In that event routine, you can do other actions but must also remember to RELOAD the timer property - or decide to set it to zero if you ran into an end condition.
The implication is that you would have a button to click that would open your recordset of slide pointers. It moves to the first record of the recordset. It brings up the first image display. It loads the timer.
The timer routine has the EOF test for the recordset and doesn't do a .MoveFirst, it does a .MoveNext, but the rest of the routine (i.e. loading the display) is the same as the button-click routine that started it all.
Which probably means you have grounds for making at least part of it a subroutine.
Hope that's specific enough for you.