My name starts with a J too and I commonly stutter trying to say it when introducing myself. I try to take a deep breath before saying my name during an introduction and say it slowly. Sometimes it works, other times it doesn’t. There’s been times when I try to take my time to relax before saying my name to try to avoid the stutter and then the person I’m talking to will joke and ask if I forgot my name, so I get where you’re coming from.