The 390 ohm resistor was just one I randomly grabbed, so as to roughly measure the voltage drop across the LED - I had no intention of specifying that as a suitable current
As I've no idea what, if anything, I'm going to do with them I've got no assumptions on the current. I would like though to light up at least one entire string, just to see how bright it is.
Incidentally, the LED's are SM (obviously) and have six pins - although only two look to be used.