We get used to remembering April 15 as our filing date, but even that is subject to change, and when you file at different times, you can expect your refund at different times, as the following two articles indicate:
On the plus side, e-filing has made filing your taxes and getting your refunds a lot quicker. And really my favorite part of thinking about taxes is thinking about getting a refund and figuring out how I'll spend the money. But there are a lot of factors that can slow down your refund. For example, if you're needing to file amended returns, this can slow you down quite a bit.
This isn't a tax blog, of course, but sometimes readers send me links related to taxes, and I try to share information when I can!