I just don't know if the surf is rougher in Ormond or St. Augustine
Probably have to check the local surf forecasts and beach-cams for each area, as conditions likely change by the hour depending on conditions.
As a newer sailor, it would be easier to get familiar with the boat and it's habits if you started on the "Gulf" side as there may be short/steep chop, but no considerable ocean swell or surf-break.
Once you get that squared away, you should be fine in either St. Augustine or Ormond.
If I recall the SC 17 doesn't have daggarboards, so shoals/sandbars may not be a big issue for you (I believe the rudders kick up if they hit the sand)
Enjoy your boat! Any boat that gets you on the water more is the "right" boat...