Thawing breast milk

Carolyn
Hi everyone!
I'm still getting the hang of this breastfeeding/pumping thing and am going back to work next week. I have a pretty good stock of frozen milk just in case I can't pump enough at work for the next day and I wanted to test how long it would take to thaw so I put a bag in the fridge last night. I put it in at 9pm and here it is at 11:30am and it's still pretty frozen. From what I've read, thawed milk should be use within 24 hours, but do you think that's from when it starts to thaw or until it's all the way thawed? If it's the first one, we might not be able to use it all!
Any advice would be appreciated! Thanks ladies!