Can I apply for a 1-year extension of my Non-O visa after returning from my trip?

Good morning Tod and fellow members. My Non-O (Guardian) and my son's Non-O (Education) visas will expire on 17 September. We need to apply for 1 year extension. I've read that you can apply when you have 45 days left on the current visas. However, we will be away from 6-13 Aug. Will it be okay if we apply on the 14th, which will around 31 days left or should we rather apply before we go away on the 6th? Also the bankbook update and bank statements, should I get that the morning on the way to immigration or can I get it the day before?. Thank you in advance