If you wear your hair short and would love to go longer between trimmings, give it a little trim right now. The moon is full and it is the perfect time. If you trim your hair when at the apex of the full moon, the growth will slow with the waning moon, which means a lengthier time between trims and -- money saved! Yay!
Conversely, if you would love for your hair to grow long, wait until the moon is new to give it a tiny little trim. As the moon is growing, or waxing full, so will your beautiful locks.