There is a small drip when the cold water is run out the faucet but turns to a steady stream after 60-90 seconds of running the shower, cold only. The water appears to be running over the end of the tub but is also on the floor around the sides. Opened up wall behind faucets and showerhead, dry walls. Caulking around tub, faucets and showerhead new, not leaking. Help!

If you have a hand turn diverter valve, take off the knob and escutcheon plate that hides the valve from the tub side. Install the knob and turn the water back on. Does water come out of the valve stem?? If so, tighten the stem nut or repack the stem with teflon rope and tighten the nut. Do the same for CW and HW. Hope it works!

Unfortunately we tried that on both hot and cold and that's not the issue but thank you

Since it only does this with cold, it has to be supply related. The water is either running down the inside tile wall or between the sub wall and finished wall. What is the inside tub wall composed of?