Depends entirely on how the software works.
Typically you can export your video as mpeg2 (DVD format codec) and then when you create the DVD it doesn't have to transcode the video when building the disc. Otherwise some software packages will transcode whatever codec you use to the correct one when building the disc, which obviously takes a bit longer to render.
However, the advantage to letting the software do it all is that if you are dealing with a long video, it might be too big for the disc. The software though is intelligent enough to tailor the mpeg2 transcode so that it will fit everything to a DVD.
So if it's not a big video, I'd just go mpeg2 and you also get full control over quality. If its larger, then just export from your timeline in the best quality that works for you in terms of disk space and the fact that the larger the file, the more time a further transcode will take.
