depends how ok you are with the clinical knowledge-so you can learn "fast" the differentials and some treatment, write the note, etc-what's required by 2cs,
if it takes more than 2 months or if clinical knowledge is far away-haven't read on medicine for a couple years - need to go the regular way 1-2ck-2cs
2cs is 'easy', dont waste time 'studying' for it, 1 & 2 are much more important and you'll have the knowledge already by the time you get to 2cs