You can only enter the start that you have been allocated, so you will need to go to your seperate areas, if you want to meet up, then the two routes join around mile 3, but it will be a bit chaotic (that said in previous years I have met friends on other starts around the 3-5 mile mark so it can happen)
time wise, it is about a 12 minute walk between the two starts, hope that helps, good luck with your race, hope you enjoy it 