How to encourage people to move faster

Our store is training a lot of employees for another store right now and we’ve been running our morning with sometimes 6 people and closing with 4-5. Most of the people for our store started when we got all these people so we don’t know what it’s like to only open with 2 people. I also don’t know what that’s like yet but I feel like I have the foresight to see that I also need to be quicker and more efficient but none of my stores ppl seem to care. One girl was talking to me about how happy she was to finish meat at 9 when we get there at 6:30. We started at the same time and I finish by 7:45-8. How can I gently encourage them that it’s about to be really difficult in the mornings when these people leave in a couple weeks and we have to hone our speed while we have the breathing room to do so?