so only water when the wooden skewer is bone dry?

Not necessarily bone dry but without wet/damp soil media obviously attached to it. And depending on your potting soil, you will most probably have a perched water table or a portion of fully saturated soil at the base of the container that will always remain wet....unless you forget to water for weeks on end! So the bottom of the skewer will always have some sign of dampness showing.

I'm not using any soil, just the 5-1-1 mix. Is that not how you're supposed to do it?

The 5-1-1 IS a soil mix...one that's intended for container growing. Potting media regardless of ingredients are generally referred to as 'soil'.....even if there is no real soil (aka garden 'dirt', loam, topsoil, etc) included in the mix.

And yes, the 5-1-1 will develop a PWT. Just much less of one than a regular, commercial bagged potting soil mix.

I hate to keep bombarding you with questions but you seem really knowledgable haha. I have a 13.5"h by 13"d ceramic cylinder planter that I keep my ficus in. It's propped up by wooden legs. It had no drainage holes but when I bought it I had a guy add two using a diamond drill bit. I will have a momentary opportunity when I'm switching to 5-1-1 to add two more. Is two enough or would four be better for drainage?

I will guess that four is better

While the Lime does require some time to finish its reaction, most of us have mixed 511 and planted the same day. If you have the time to wait, do so; if not, no problem.

Josh

Re the extra hole - don't bother. One is adequate. Plants don't care if it takes 6 minutes vs 60 seconds for a pot to drain. More holes affect only the speed with which the pot drains, not how fully it drains. IOW, if you have 1 hole in the pot bottom and a 4" perched water column at container capacity (the amount of water remaining in the pot at the point in time where a fully saturated medium has just stopped draining) and you add 5 or 10 more holes, you'll still have a 4" perched water column at container capacity, which = no return for the extra effort.

The best place for a drainage hole is through the bottom AT the sidewall. That way, if needed, you can remove a lot of excess water by tipping the pot. The shaded area in the image below represents saturated soil. Compare B to A to see how much difference the simple act of tipping the pot to a 45 angle makes.