training for a sprint finish

For your first tri I would not worry about training to finish with a sprint. If you have the energy left at the end of the run, pick up the pace a bit and smile so you don't look (as I do in about half my finish photos) like you're about to puke!

Finishing a run or tri with a sprint is a matter of not just training but race execution. Solid training in all three sports makes it more likely you could dig up a strong finish if needed; for example, to get onto the podium, meet a time goal, or pass a rival. But it's also a matter of how the race plays out. Even the pros do not always manage a graceful finish--I've personally seen Chris Lieto walk over the finish line, for example in a race that was less than a half-ironman in length. It's not at all uncommon for Ironman pros to stagger the last few hundred meters, completely spent. If you execute a race perfectly, at best you'd probably be able to pick up the pace a bit and finish strong.

In my younger days I used to have a nasty kick, but only in really long races, like the last mile of a marathon. I also had a pretty fast last mile of my half ironman last year. I suspect it's due to 1. solid fitness 2. happening to have a talent for endurance (I only look good/fast when others are staggering with exhaustion) 3. Being able to dig deep and really suffer when motivated and probably mostly 3. never really getting pacing exactly right for long events--maybe I start too conservatively because, quite honestly, those long distances scare me a little. I kick to celebrate my survival!

Thanks everyone for the great advice. train for the whole event not just the last 50 metres.
The most important thing is have fun with it.

I agree with even pace or negative split theories, but the adrenaline rush of knowing the finish chute is near can give me the strength to find something left for a good kick toward the end. I can usually reel in or drop a nearby racer in the final moments this way.

It's an interesting mental thing that nearly everybody has enough for a relative kick at the end. You won't see many people walking the last 200 yards of a triathlon of any distance - even the dog tired IM walkers will break into a run even though a few miles before they were out for the count.

I think a sprint finish may have a significant impact on how you feel at the end of the race and maybe on your recovery too. Perhaps push on an extra bit but I don't think you'll gain too much from going flat out and the potential downsides are considerable.

Also, the finish chute is a nice place and worth remembering - you can't take much in if you're red lining it down there.