Is Lottering river crossing dangerous and very deep if we do not make it at low tide? Is it worse than the Bloukrans River?

How long does it take from low tide to “middle tide” which is still safe to cross.

Also the Bloukrans river. We intend to leave at 4am to make it in time for low time i.e. 0730. If we only reach at 0900am, is it still safe to cross?