For most tropical fish, feeding once a day an amount they can consume in 2 to 3 minutes is correct. Don't be tempted to feed them more than once a day and its usually a good idea to randomly skip a day, maybe once a week.
I've had silver dollars in the past and don't remember treating their feeding differently than my other fish, but there's always the chance of members on here more experienced than me who may know some special tips about feeding silver dollars. In the past there have been some concerns expressed about bloodworm being a bit rich if fed too much but I don't know whether that concern would be true for silver dollars.
~~waterdrop~~