A good rule of thumb on lps is to start them at the bottom and work them up over time. Running a 250W MH (DE or SE?) on a 210, you could probably start them a few inches off the bottom. I'd start both piece low and move them up. The acan is probably going to like moderate flow and medium light when it is all said and done. I've got a rainbow echinata that I've had for about three months and and encrusting monti (though not a danae) that are both on top of the sand bed under 250W DE AB 10K's and VHO's.
FWIW, I'm one that typically only temperature acclimates corals. Once the temp in th ebag is the same as the tank, I'll usually drop them right in. Acclimation definitely won't hurt, though. Especially if the salinity or alk are quite different from the stock tank the corals came from and your tank. Wide alk ranges can cause things to not go well (as I think a number of people from the last frag swap in Tn found out the hard way). If you keep your tank at 8 dKH and they came from 12 dKH, the temp acclimation and drop may be an issue, for example.