In my experience they do not consider it late until it has actually passed the deadline you were given (or the deadline you stated you could complete the work in)
They also do not consider it late if you have 24 hours or even 1 min left to get the finished product to your buyer. I know this for a fact, as I had an order the other day I had to type up furiously because the buyer forgot to give me her birth info and she didn’t ask her question in the form it needed to be in for the type of reading she wanted. I got her correspondence one hour before the reading was due, and I delivered it 7 minutes before it was due. I didn’t get penalized and it was not late.
Of course, I don’t like working that way, as it is pretty stressful, and with my luck, something would go wrong and I couldn’t deliver due to the website crashing or my isp taking a lunch break! LOL I try to get my orders done at least a few hours before they are due. I increased delivery on most of my Gigs so that I don’t feel stressed out to rush and give mediocre service. I typically write over 10k characters and 5k words in my readings, so it takes me a while to get done, and really, I need to streamline my readings more. Hard to do with my chart though! LOL