My TV wall mount instructions say 7/32" bit, but I only have 15/64". Can I use it, or is that too big?

Using a 15/64" bit when 7/32" is specified will make the hole too large. That 1/64" difference means the screw threads won't have enough material to properly grip, especially in wood studs. This significantly compromises the mount's stability and could cause your TV to fall, potentially injuring someone or damaging the TV. Always use the specified drill bit size; a new bit is inexpensive compared to a fallen TV. If you're drilling into drywall with specific anchors, the bit size is even more critical for the anchor to expand and hold correctly. Don't guess here; get the right bit.