As per my opinion immediately after passing CS Executive stage one should finish his/her CS Final coaching and gave at least one attempt. After clearing 1 or 2 group one should start searching training.
However if meanwhile a good opportunity comes than grab it…as quickly as possible. Reason behind this thinking is ---training in CS is not very lengthy and just for 1 month as compared to 36 months training in CA, which gives an opportunity to a CS student to finish his/her final early.
RG