I have had a few times where this has happened, most of my switches are not so abrupt though. Lately at the end of my mania I will have a switch either overnight or an immediate one in the middle of the day. Unfortunately that switch turns me into a monster whos only mission is to die(but still alive so far thanks to cops and drs and lifeflight lol) After that last mania I spent time ultra rapid cycling for a couple of weeks in hospital so it would switch more than once a day and then I hit depression like a brick wall and didnt get out of bed for a week except to walk to the dining area at meals. Finally one afternoon I got out of bed and was fine, happy, normal. Got to go home just a few days later.

I have never had a medication have a lasting effect on me immediately except extremely sedating meds. I am not trying to say its not possible. With my last med change I felt great immediately, but it was that hope, the excitement for positive change that made me feel that way. It didnt stay that way the whole time, there are still rough patches but I am still doing better than I was before and that initial incredible happiness was great.