You'll get pressure as soon as you crank the ignition, and remember you have about half a litre of oil that will be lurking in the pump, galleries and oil filter. The Caterham Build Manual idea is, I suspect, mainly incase some numpty self builder forgets the initial fill in his race to hear the exhaust crackle and pop. It is not unexpected that Toyota engines can sit dormant inside a vehicle in the supply chain for several months without turning over.