On our Frontier cart there is a metal loop that serves as both purposes, I believe. It is in the position of a shaft stop, but the metal loop is also used for the breeching (footman's loop). It's in the proper position for the stop, but is a little more forward than I'd like for a footman's loop. So, maybe your cart has this?? Do you have pictures? Usually there are 1 for each. If you're using a show cart, there may be neither. One of our show carts came like this. I don't feel comfortable with this set up. I was amazed how well the wrap straps held the cart in place.....assuming you had the plastic-like shaft cover the straps wrap around. Iowa valley Carriage has most of this hardware available. We put both on our carts.
Before we hitch our horses, we usually have them ground driving, pulling a tire around by the traces and in harness, and then going in "fake shafts" before the actual hitching. Until they're totally bored with all of these do we put them in cart. Before hitching, be sure to have a helper hold the shafts on the opposite side as you to support in case something goes wrong. I'm sure you've done all this and are ready. Have fun and post pictures.