Indeed, thanks for this alert Ernst,
Besides your message: “it is not exlude that the eclipse could begin some days before the calculated date August 4th”
it could also be later. According to the work of Leedjärv et.al. (A&A 1999) it seems the orbital period has a tendency of increasing between the eclipses due to a possible mass transfer or mass ejection. (Approximately 1% per two former eclipses).
Anyway we hope the weather conditions will be favourable at the very moment of the (calculated) beginning of the eclipse.
Usefull weather info with “observation location” input possibility:
http://www.meteoblue.com or http://www.meteovista.com/international/4220/0