Well that depends on the sequencer you use, delay and buffer sizing. Setting may need to be changed when tracking vrs. mixing. For me personally when tracking I like to set as low a buffer as possible, but not so low the your system will explode and be brought to its knee's, so lets say a decent tracking buffer of 128, which should roughly equate to around 4ms of latency, then a mixing buffer of 512 which translates to around 6.x-7.x ms latency.
It really depends but those two settings are pretty general, of course there are many things that can change this, one being track size and audio count etc.
Changing these settings wont hurt a thing, you can always change it back, but I can say one thing for sure, if you have a half decent sized track count, I wouldnt bother with trying anything under 128 buffers, this will undoubtedly cripple your PC
YMMV..