I love Crinums and have plenty of them in sand, as you said sand is among my favorite substrates.
Crinums are odd in that planting with roots already begun seems to induce rot; I really have no idea why. They will quickly develop wonderful root systems that improve the substrates and really help the substrate remain oxygenated and provide a good deal of filtration.
I would wait at least 3-weeks before dosing anything and even then, it may be a while before anything is really necessary.
With properly cured wood, an easy test is the PP test; I do not see any reason not to start adding it to the tank.
Once the Nitrites get to zero and you can pass the PP test; I figure about 3-weeks, it would be nice to see the ORP value go up a bit…
Unfortunately there really are no good ways to speed up the biological filtration part.
You should be ready to go, since you won’t be able to the add critters gradually, so you may require extra water changes at first to let the system keep up. Stay on top of the Nitrites, keep the pH under 7 for the time being and be very careful with the food, you should be fine.