Dillon led the 43 drivers that took to the 2.5-mile superspeedway with a speed of 203.592 mph. Stenhouse clocked a best speed of 203.192 mph.
Defending Daytona 500 winner Denny Hamlin was third-fastest (202.684 mph), followed by Erik Jones (202.525 mph), who was fastest in the final Busch Clash practice earlier in the day, and Martin Truex Jr. (203.379 mph).
The second practice will take place later this afternoon from 3 to 3:50 p.m. ET.