Training is a little bit exhausting/intimidating because it's a lot of information thrown at you and you'll never remember it all. Stay positive, communicate with your trainer if something is specifically confusing or there's something they could change to help you learn better: i.e. I asked my trainer to allow me to finish a drink before critiquing/telling me what I did wrong instead of stopping me midway, because I'd remember it better.

When your first real day comes along, it's perfectly normal to still feel like you don't know everything. Use your fellow partners, ask a bunch of questions, and embrace being deployed at positions around the store that you aren't solid on yet. You'll learn as you do.

In general, both partners and customers will overlook slowness/newness/not knowing something as long as you are willing to learn and adjust your behavior and keep a good attitude.