When the date of dedication is unknown, the Dedication Festival may be observed on the first Sunday of October (3 October), or on the Last Sunday after Trinity (24 October), or on a suitable date chosen locally.
Dedication Festival

http://almanac.oremus.org/2021-10-03

Gold or White

Principal Service
Genesis 28.11-18 or
Revelation 21.9-14
Psalm 122
1 Peter 2.1-10
John 10.22-29

Third Service
Haggai 2.6-9
Hebrews 10.19-25
Morning Psalms
Psalms 48, 150

Second Service
Jeremiah 7.1-11
Luke 19.1-10
Evening Psalm
Psalm 132

Collect

Almighty God,
to whose glory we celebrate the dedication
of this house of prayer:
we praise you for the many blessings
you have given to those who worship you here:
and we pray that all who seek you in this place may find you,
and, being filled with the Holy Spirit,
may become a living temple acceptable to you;
through Jesus Christ your Son our Lord,
who is alive and reigns with you,
in the unity of the Holy Spirit,
one God, now and for ever.

Post Communion

Father in heaven,
whose Church on earth is a sign of your heavenly peace,
an image of the new and eternal Jerusalem:
grant to us in the days of our pilgrimage
that, fed with the living bread of heaven,
and united in the body of your Son,
we may be the temple of your presence,
the place of your glory on earth,
and a sign of your peace in the world;
through Jesus Christ our Lord.