First of all applying with CS scores is not necessary but without it your interview chances will drastically decrease
and you are most likely to waste your money in applying to programs
because according to the program directors survey an NRMP publication (2012)... majority of the programs need your CS scores to even consider you ....like
- FM considers 91 percent of people who have their CS scores in hand when applying
- IM ----84 %
so you are most likely to get filtered out when you apply without CS scores
what the other 10-15 % had such exceptional scores on STEP 1 or had a very strong CV with handful no of LORs and research to go with the scores ....
Now if you apply late you will then again you have a limited chance to secure interviews as most competitive programs had already filled their slots for interview with the students who had their application completed on time and applied early .
So it depends on you ....if your scores are very good then apply .... and if not better apply when you are ready completely