Vespers, unless preceded by another service (such as the Ninth Hour), always begins with the full beginning:
Blessed is our God…
Glory to Thee, our God, glory to Thee.
Heavenly King…
Holy God. All-holy Trinity. Our Father.
For Thine is the kingdom…
Lord, have mercy. (12x)
Glory; both now.
O come, let us worship…
Bless the Lord, O my soul…
If Vespers is preceded by another service, then it begins as follows:
Blessed is our God…
O come, let us worship…
Bless the Lord, O my soul…
This concept does not change during the Paschal season.
From Pascha until Pentecost, Glory to Thee, our God, glory to Thee. and Heavenly King…
are not said at the beginning of services.
During normal periods, the Typica is after the Sixth Hour. During fasts it is after the Ninth Hour.
The Octoechos is not used from Lazarus Saturday until the Sunday of All Saints.