I'd like to convince some friends that 'peak oil' most likely took place in 2008.

Why?

I don't mean that rhetorically, either, but as an honest question: for what reason do you wish to convince them of this particular proposition?

If you want them to engage in a particular behaviour, such as consuming less oil, then directly addressing that behaviour is almost certainly a more productive approach. For example, simply noting that: (a) oil production seems to be struggling to keep up with oil consumption; (b) that led to high prices in the last few years; and (c) prices are still relatively high and likely to rise in the near future is much less controversial and uncertain, but should have much the same effect in terms of raising awareness regarding oil consumption.

By contrast, if you want to induce a particular mindset, such as believing that civilization is ending, then the timing of peak oil is only one tiny fragment of what you'll need to convince them of. In that case, you're not merely trying to convince people of a physical fact, but of your interpretation of that fact, which is a much harder task. Your interpretation likely relies on a hundred assumptions and leaps of logic you've made, and getting your friends to accept those may be no easy task.

So ask yourself whether you want to convince them of the idea that oil availability is permanently dropping, or of your particular beliefs about what that will mean for society. The first of those is pretty easy - show them a few graphs of prices and rig counts - but the latter is something that will be extremely difficult to provide an evidence-based argument for.