I'd get them now. Whether you compete in a triathlon is largely irrelevant as you should only be unclipping once in transition and two weeks is plenty of time to figure out how and when to unclip.

To set some expectations, riding with cleats is more comfortable but it won't make you any faster or give you any extra power in a triathlon. The ability to pull up on the pedal can provide some extra power when standing on a steep hill or sprinting, neither of which you'll be doing in a triathlon.

If you get them now and for some reason don't like riding with them you could always take them off for the race but it's really not a big deal to ride with clipless.