Consistency! Plenty of time to get marathon ready so no need to rush. Run 3 times a week, maybe 4 if that is what your plan calls for. Midweek runs are strength builders but for a newby, just get the time in. The weekend runs are to build endurance. Do not worry too much about pace. You want the weekend runs to be conversational - meaning no huffing and puffing, you could carry on a conversation with the effort during the run.
Start with the 5k program then maintain until time for the half program to kick in.
EQUIPMENT - get to a running store and have a qualified person fit you to a pair of shoes. The big box sports stores are not running stores. Log your miles in your shoes and only wear your running shoes to --- run. Plan on retiring them around 350-500 miles. Also allow them to dry a day before running in them again. Note that most all shoe manufacturers have a low, mid and high end of most every shoe design. Go for fit but if budget is an issue then see if there is a cheaper version of the same style.
Avoid cotton. Go to a sports store and buy a tech shirt and shorts. They will have a name like dri-fit, etc. They cost a little more but your body will thank you this summer.
Get a timer watch or a Garmin to help you track time intervals.