I would wait for others that are MUCH more qualified than me to advise you on a path...BUT if it were me I would add the sodium bromide 4 days before you are going to be gone...and before that(starting now) i would raise the FC level to 15ppm and keep ith there while brushing the pool and vacuuming it every day. The SB is available in most pool stores and is not expenisive. They suggest 4oz per 10k gallons...but if you have a nasty problem then they suggest 8oz per. It comes in 1lb bottles and is granular..I added mine into the return stream..I would not pour it into the skimmer. So you put in your 80z and then add a gallon or more of bleach...and after an hour or so check your FC levels and add bleach if needed...and then brush and vacuum more. After that its just a matter of monitoring your FC levels...keep hem high and expect them to drop ALOT...after 4 days and while you are gone you just keep the levels up until no more algae. I found it to be gone after 4 days...but i kept my levels up after that...

cliff notes version...since you are going to be shocking anyway and keeping the levels up...adding the sodium brode won't hurt...and it may solve the problem....clorine alone will not kill mustard algae.