DAS is good for 60 days. You only need to connect within that period if you want to schedule the Advanced Selections.
Some folks have reported being able to schedule Advanced Selections more than 30 days out if they have an onsite stay planned. I've seen several reports indicating limited choices if your park date is close. So you might consider renewing your DAS and setting up the Advanced Selections for the earlier dates, and then every couple of weeks check back to schedule for later dates.