Not to naysay the advice you got, but I think it's going to depend a lot more on WHERE you start shooting competitions and with WHOM than which game you try first. I've never shot IDPA, but I found it very easy to start off in USPSA/IPSC because the participants at my local matches were friendly, welcoming, and willing to show me the ropes.It was recommended by a local gunsmith(McBrides) to start IDPA since it's the easiest and cheapest to get into. His wife is a 6x' champ and comp shooter and he used to be or maybe still is a judge for comps. So I took his word for it.
If you've been searching around on youtube than you may have already found them, but if not, then Powerfactorshow, is a great resource for getting into shooting sports like IDPA and USPSA. Rick and Steve are extremely knowledgable and fun to watch. Start at the beginning and you'll learn everything you need to know about the two sports.Usually what i do is look stuff up online, read about it to get the basic concept then I youtube it for the visual understanding.