Oi Elias, desculpe estar tomando teu tempo, mas não resolveu. Não sei se fiz as alterações corretas.
By calendarioIni = By.cssSelector("#ctl00_ContentPlaceHolder1_imbCalendarioIni");
wait.until(ExpectedConditions.presenceOfElementLocated(calendarioIni));
driver.findElement(calendarioIni).click();
By dataIni = By.cssSelector("#ctl00_ContentPlaceHolder1_calendario > tbody > tr:nth-child(3) > td:nth-child(5) > a");
wait.until(ExpectedConditions.presenceOfElementLocated(dataIni));
driver.findElement(dataIni).click();
By calendarioFim = By.cssSelector("#ctl00_ContentPlaceHolder1_imbCalendarioFim");
wait.until(ExpectedConditions.elementToBeClickable(calendarioFim));
---->>>> driver.findElement(calendarioFim).click();
By dataFim = By.cssSelector("#ctl00_ContentPlaceHolder1_calendario > tbody > tr:nth-child(7) > td:nth-child(7) > a");
wait.until(ExpectedConditions.presenceOfElementLocated(dataFim));
driver.findElement(dataFim).click();
O erro ocorre na terceira linha do terceiro bloco.
org.openqa.selenium.WebDriverException: unknown error: Element is not clickable at point (450, 398). Other element would receive the click: <a href="javascript:__doPostBack('ctl00$ContentPlaceHolder1$calendario','6181')" style="color:Black" title="03 de dezembro">...</a>