Clean out your fabric softner dispenser and put the vinegar in there. It'll do the rest, releasing it at the right time. Go spend your time doing something meaningful instead of watching your washing machine waiting to add it
Don't use too much vinegar. Your cloths will smell of it when dry.
Don't use Dawn in a washing machine. It's too concentrated and can produce too many suds especially if you have soft water.
Use hot water with a quality liquid detergent. I like Tide Clear.