When the date of dedication is unknown, the Dedication Festival may be observed on the first Sunday of October (6 October), or on the Last Sunday after Trinity (27 October), or on a suitable date chosen locally.
If Sunday 27 October is observed as the Last Sunday after Trinity:
The Last Sunday after Trinity

http://almanac.oremus.org/2019-10-27

Proper 25
Sunday between 23 and 29 October inclusive
Principal Service
Continuous
Joel 2.23-32
Psalm 65*
2 Timothy 4.6-8,16-18
Luke 18.9-14
(or)
Related
Ecclesiasticus 35.12-17 or
Jeremiah 14.7-10, 19-22
Psalm 84.1-7
2 Timothy 4.6-8,16-18
Luke 18.9-14

Third Service
Psalm 119.105-128
Isaiah 59.9-20
Luke 14.1-14

Second Service
Psalm 119.1-16
Ecclesiastes 11, 12
2 Timothy 2.1-7
Gospel at Holy Communion:
Matthew 22.34-46

(or) Evening Prayer on the Eve of Simon and Jude
Psalms 124, 125, 126
Deuteronomy 32.1-4
John 14.15-26

BCP Collect

O God, forasmuch as without thee we are not able to please thee; Mercifully grant, that thy Holy Spirit may in all things direct and rule our hearts; through Jesus Christ our Lord.