Typically it's a matter of weeks, and Apple and Adobe aren't too far apart when adding support. If the sensor is not brand new, support can be added more quickly, if not, it takes a little longer. It's not as if you will have to wait half a year or so for support. The only major difference between the two is that there are two, three brands such as Sigma and Fuji that Apple does not support and seemingly has no inclination to add support to.* But as long as you stick with either Canon or Nikon that won't matter to you.
* This will put me in a bit of a pickle: I plan on getting a Fuji X100s next, and I don't get along with Lightroom's user interface and the necessity to manage my own files.