To get the BEST from your Elodia candle, the 1st burn should definitely be longer than 15 or 20 minutes. The longer your candle burns, the bigger the opening for future use. Melt all the way to the edge. Once the candle has formed a melt pool all the way to the edge of the container, that will help set the burn pattern. 
 

• Trim the wick before each use.
• Let the wax melt all the way across. Once your candle's lit, don't blow it out until the top layer of wax has melted all the way across. 
• Keep the flame away from moving air.