We set the "Grid Start Date" for the GAD to be "today." But, as you can see from the attached screenshots this is not actually giving the option to book on today. It jumps to the next day for booking. Can you please clear this up for us?

I count 6 days, I am guessing you have set Thursday as a non-booking day and also set Hide non-Booking days = Yes.
Also, if you wish to allow same day booking you need to set the resource's 'Disable Dates Before' = Today. The default is 'Tomorrow'.

Thanks, we figured it out. You have to set "Disable Dates Before" to "Today" for the resource if you want the current date to display.