Change from 25fps to 24FPS

Hello. I am in the process of doing this myself. The process is involved but it works. First use premiere to make a .tif sequence. Make sure to export in 25 fps. Then I use OpenDCP, a free to use DCP maker to make J2C conversions of the .tifs in 24fps DCP package. Then you can do the change the speed and the pitch 4% in Audacity or Audition. 

This process is a little more cumbersome but it does the trick. 

I've just created a new sequence at 24fps , and dropped the timeline contenta from the 25FPS sequence into this new sequence and it's the same length and (seems to) play back the same? Does Premiere now automatically handle this or am I missing something ??

Premiere will throw away one (1) frame per second if you do that and static shots will look good while motion, such as vertical panning, something in image moves vertical, someone moving hands while talking/acting will look bad and "jumpy".

Export the 25 fps timeline to let´s say Apple ProRes or GoPro CineForm as 25 fps. Import that file, right click on it and choose Modify > Interpret Footage and set Assume Frame Rate to 24 and click OK. Now, place the file on a 24 fps timeline. This will get you all frames, all motion will look good.

To fix the audio pitch, export the audio from the 25 fps timeline and use Audition to change the pitch by stretching it and using a pitch filter.. You want the length of the 25 fps audio to be the same as the duration of the 24 fps timeline. If you use background music, i prefer to export the 25 fps audio without music and then add it again in the 24 fps timeline.