Can I buy On-Load Octopus card at MTR centre at airport or North Point @ 8AM?

I am landing at HK 5:50 PM and I read at MTR website that MTR customer service centre closes by 7 PM. Will I be able to buy On-Load Octopus card at North Point station after 7 PM or 8 AM? MTR site shows just 5 stations only that are open from 10:30 only.