Make a repeating time trigger. Disable it once it's fired 3 times.
You can use a static variable declared in your trigger function if you need to count there (or a global variable, but that's kinda gross). You can use a global variable for the Trigger.
To make a global variable, move the declaration (eg. Trigger myTrigger;) outside of any function (preferably at the top of your source file, after the #includes, but before your first defined function. To make a static variable, declare it inside a function like you would any other variable, but add static in front, and be sure to include an initializer.
I'd recommend that you disable the trigger once it's fired 3 times rather than simply stop executing the body of your callback function. Otherwise, the trigger will still be taking processing power every cycle to cehck if it fires, and will keep calling the callback to do nothing.
Edit: ... or just create three seperate triggers with three seperate callback functions (actually you can probably use the same callback for all of them), and change the time associated with each trigger slightly. Easier, but less flexible.