I don't accept the way the "year-for-a-day principal" has often been applied to prophecy. In the Bible whenever a year-for-a-day is used prophetically, there is always a period of literal days (40 days spying out the promised land) with significant, observable events at the start and end -- events that people could see (the spies departed to spy out the land; the spies returned from spying out the land) -- along with a corresponding period of literal years (40 years wandering in the wilderness) also with significant, observable events at the start and end (the Israelites sent back into the wilderness; the Israelites enter the promised land).
When people try to apply the year-for-a-day principle to prophecies that lack a period of literal days (such as the 2300 days), or lack observable starting and ending events for the period of literal days (such as the 2300 days) or lack observable starting or ending events for the period of literal years (such as the 2300 years) they are merely speculating without regard for the way the Bible applies a year for a day to prophecy.