You have the option to enable a welcome message by going to Settings and selecting the channel settings for Front Chat. You'll then be able to customize and enable the message:

It will look like this when visiting the site, and then opening the chat:

You can also read a bit more about further customization in setting in the help docs, and more advanced use case in the developer docs.

I hope this was helpful, if you have any other questions let me know. Enjoy the rest of your day!

Best,

--Leslie