To answer your question, it takes a long time to start seeing oil at the rockers even with the engine idling. I'm pretty sure you could get there with the hand crank (and the plugs out), but there is no way I would want to crank on it that long.
Because of the way the camshaft meters the oil to the rockers, the oil gauge actually comes up first, before any flow is visible to the rockers. I've never put a stopwatch on it, but I'd guess it's close to 30 seconds at 1000 rpm before the rockers start oozing oil; so something like 500 turns of the crankshaft. And that's for a normal start, where the oil filter is already full, etc. (I often leave the cover off after checking the valve lash, and start the engine to make sure all the rockers are getting oil. Never had a shaft plug up on my own engines, but I have seen it on others.)
IMO the bit about most engine wear being at startup is a myth, often repeated by the likes of Slick-50 and STP (both of whom have been censured by the FTC for lying in their advertisements). Also, on the TR2 (unlike most engines), the oil pump literally sits down under the oil; it doesn't need to be primed. Just spinning with the starter (plugs out) puts very minimal load on main and rod bearings (which of course you greased during assembly), and not much load on the camshaft journals, etc (due to the low speed), which again were generously greased. "Back when", many engines ran with only drip lubrication to those points anyway. If you attend any antique power show, you can see a long line of engines with their rockers fully exposed to the outside, and no lube at all beyond the occasional squirt (by the operator) from an oil can.
Anyway, I've always just spun it with the starter until the gauge comes up; then put the plugs in and started it. I've run well over 100,000 miles, and never seen any signs whatsoever of excess wear on initial startup. Besides which, you actually want some wear right at initial startup, that's the "bedding in" that the manual talks about, and the reason you don't use super-slick oils for the first few hundred miles.
A stock TR2 is going to have it's life shortened a lot more by the primitive air filters, than by being started without oil pressure.