Yes. Always preheat the grill before cooking. Follow the preheating instructions outlined in the owner's manual.
Quick Tips for Preheating:
Sear – preheat with all burners set to HI for maximum cooking grate temperature
Barbecue – preheat with all burners set to LO for a lower starting grate temperature for grilling foods slower
Indirect grilling – preheat one burner only on the side opposite where the food will be placed to allow the slowest and lowest grilling for larger cuts of meat
Roasting – place the warming rack on the lower supports and use burner(s) directly under the food on LO or indirectly for lower temperature cooking. This will allow more heat to circulate around the food during grilling.