It is not possible to specify a date when the name of a village changed, because it never did. "Misslitz" is the German name for the village, used by the Austrian government. The Czech name was "Miroslav" and was used interchangeably, depending on who was talking. In the late 1800s (1870 on, maybe), the Czech names started to be used in official documents, such as baptismal records.
You can go back a few decades, and both the German and the Czech spellings would show variations from these two spellings. You cannot say "they used Misslitz on the document so they must have been there in 1850" or "they used Miroslav on the document so it must have been after 1890". The style of handwriting on the document would give you a better indication of the timeframe than the spelling.
It's like Prague -- that is not the Czech spelling, Praha is.
More importantly, when I go to see if any Miroslav records are on actapublica, the first ones showing up are Evangelical. If your ancestors were not Catholic, then you might be in luck there. The second choice yields the Catholic records.
If you give a name and a date, even if approximate, the posters are willing to give it a try finding an original record. Which brings up the question -- why is it important to narrow down "when" the name changed?