Yeah the "don't buy anything till later" rule is a lot more applicable when you're talking to a beginner who is convinced he needs really exotic effects. The point is to remind you that having a somewhat decent command of your instrument comes before you start playing with toys, and to keep you from spending too much in case you find you don't like it later on. Overdrive and reverb are not particularly exotic (they come standard on many amps), and I think wanting those pedals after 6 months of playing is pretty reasonable. Otherwise I wouldn't have recommended 3 of them.
That said, if you start to feel you need a compressor pedal or a volume pedal, take a deep breath, count to 10, and then wait a few years.