Find time to vist... nothing long, but maybe what's your favorite food. If it's a small class include everyone, or choose a section. Speaking, at first will be easier than them playing. It will prepare them to play alone, even it's just on mouthpiece.

Use a rock beat off of a keyboard to do exersizes.
Counting or naming music. Count rhythms with enthusiasm.
Have a fun fact or quote for the day.

Have individuals "solo" down the row. It can be a whole note, a rhythm for four counts. Put a 4 count rest in between each person to prepare the next person or give praise.

Have fun doing what you doning. Students will feed off of you enthusiasm. Smile, laugh and give praise!