CathInfo.com

I don’t see where this website says what time the Palm Sunday Mass stream begins either.
Any SGG people know?

They must announce their Mass times there somewhere?

The Holy Week schedule at SGG is the following (all of the ceremonies below should be on the SGG webcam):

Monday of Holy Week: 

School High Mass: 11:25am (Vespers immediately follow)

Tuesday of Holy Week:

School High Mass: 11:25am (Vespers immediately follow)

Wednesday of Holy Week:

Low Masses: 7am, 8am, and 9am (they might not webcast all of these, but if they don't they will probably webcast at least the 9am) 
Vespers follows the 9am Mass

Tenebrae 6:30pm

Maundy Thursday:

Pontifical High Mass: 9am
Ceremony of the Maundy: 12:15pm
Tenebrae: 6:30pm

Good Friday:

Stations of the Cross: 11:25am
Mass of the Presanctified: 12:15pm
The SGG webcam will likely be on starting at 11:25am and ending after 3pm
Tenebrae: 6:30pm

Holy Saturday:

Easter Vigil: 8am (SGG webcam will be on the whole time until the conclusion of the Vigil around 12pm or 1pm)

Easter Sunday:

Matins and Lauds of Easter: 5:45am
Low Mass: 7:30am
Pontifical High Mass: 9am
Low Mass and Benedication: 11:30am
Paschal Vespers: 6:00pm