I'm not as confident in what pharmacists know -- they only know what pharmaceutical companies teach them. Here's my opinion, but there are other opinions out there obviously: I would taper off the Zoloft as slowly as necessary until you stop and have no significant withdrawal symptoms. None of these drugs work the same, and you're switching to a wholly different class of drugs. Now, many people have no trouble at all stopping and starting meds, but if you stop a drug while starting another, how will you know if you're suffering withdrawal from the old drug or side effects of the new one? To be safe, I'd stop the old drug until it's successfully done before starting the new drug. I'd also ask if your doctor is a psychiatrist or a regular doc, because that's an extremely short tapering schedule. All my psychiatrists have used at least a 6 week taper.
Your pharmacist will know and the manufacturer has a site for each drug and they will know.