I dont know what time HEA is, but the boat launch to MK is very close to the HDDR venue....only issue is the timing of the boat which runs every 20 minutes or so. Going with worst case scenario, I would plan 45 minutes to get to MK. Best case 15 minutes. The boat ride is about 10. Add another 5 - 10 to walk to HEA venue...so in total 30 - 60 minutes.