When referring to the homepage, a trailing slash after the hostname is optional since it leads to the same content ("https://example.com/" is the same as "https://example.com"). For the path and filename, a trailing slash would be seen as a different URL (signaling either a file or a directory), for example, "https://example.com/fish" is not the same as "https://example.com/fish/".
Hey Ted, thanks for the great questions! The peak times refer to your particular time zone, if you are targeting an audience that resides in the same zone as you. You can also use tools to find out when most of your audience is online. For example, Facebook has this built into their Page Insights. For Twitter, you can use https://followerwonk.com/. Many social posting tools also offer this functionality.