Absolutely, just give your AFCO a call.
WS has a two year wait anyway - some applicants join the RNR whilst waiting to join as a Warfare spec.
Does this mean that there is a shorter waiting time to join the RNR as opposed to the RN as a Warfare Spec?
Also if this was the case and hypothetically one chose to switch their application from RN to RNR for Warfare Spec to get in quicker, would it be an option at a later date to transfer across to RN as a Warfare Spec if there was availability?