At early dawn (ορθρου βαθεος). Genitive of time. Literally, at deep dawn. The adjective βαθυς (deep) was often used of time. This very idiom occurs in Aristophanes, Plato, et cetera. John 20,1Markus 16,2

Which they had prepared (α ητοιμασαν). Mark 16,1Lukas 23,56