Step by step transition advice

For starters are your bike shorts the traditional bike shorts with a big pad or are they tri shorts? Traditional bike shorts will make for a soggy diaper feel on the run. 

Secondly, pulling a shirt and socks on to a wet body can be challenging. Consider rolling the socks down so you can roll them on. As for the shirt, no suggestion there, I use a tri top that I wear under the wetsuit.

Most importantly, have fun. I've not done an off-road tri but I'm working on getting there.

Shirt will probably be difficult to get on since you're wet.  Try it in advance.  I'd suggest rolling it and your socks.

I'd ditch the snack unless you really need it.

1,  It's a lot faster if you have tri shorts and a tri top on underneath the wetsuit.  You'll waste a lot of time putting a shirt/top on.  I would add clothes in T1 "only" if the air temp was going to be pretty low.

2. You don't need a snack for a sprint.  Maybe some Gatorade in a bottle rather than the water.

3. You need a race belt with your bib number attached.  You'll grab the race belt in T2 before you go out on the run.  Put it on around your waist as you are running out of T2.