MabiPro: The Authentic Old-School Mabinogi Experience

I'm trying to transfer my ego from one sword to another, and I bought that million gold potion to ensure levels aren't lost. Do I just feed it to the ego before spirit transfer, or will it automatically be used during the transfer? I'm just making sure since the potion is a pretty penny. Thanks!

Update: So yeah, just talk to Tarlach with it in your inventory while doing the transfer, he will use it automatically. His dialogue is translated, so no random clicking of buttons fortunately.