What he meant was that: you're using the wrong method for the problem. Although, He might have interpreted it as though you wanted to build the oscillator solely using IC's.
Basically, I'd say that you'd need the 555 to start the oscillator circuit at a specified time, t, wherein it just runs on free will. So, it would just really be a single trigger starting the oscillation, and a logic gate trigger to maintain it.
I can't help anymore, I don't know enough about micro controllers at this stage.