Summoning the Wings of Wren, you gain a fly speed of 10 feet until the start of your next turn (at which point you begin to fall). If you cast this spell while airborne, the spell fails to provide you with a fly speed, but you can subtract the spell's fly speed from the total distance when calculating fall damage.

The spell’s fly speed increases when you reach higher levels. At 5th level, the fly speed increases to 20 feet, and at 11th level, the fly speed increases to 30 feet. When you reach 17th level, the spell will provide you with a fly speed, even if you are airborne while casting the spell.