I also recommend using a timer and strictly keeping English only or Japanese only during those times.
It’s basically your time to test drive all the phrases you’ve been learning, like introducing yourself, talking about your hobbies and job, asking if they are Genki and how their family is doing, etc. So you could even go as far as writing down a list of things you want to say so don’t forget/freeze during the convo.
Mostly I recommend putting all of your fear behind you and just wholeheartedly trying to communicate and not worry about doing it wrong. I’d even suggest not having any electrical dictionary available at first so that you don’t interrupt the flow of conversation. They didn’t understand a word you used? OK! try to work around it, that kind of thing will happen a lot and you won’t always be able to bail yourself out with a dictionary. You will undoubtedly make many mistakes but the more mistakes you make the more you will learn and build confidence.