Gurfateh
Guru Granth Sahib Ji enjoyed the status of Guru from the time they came inot beeing.
Reference:: Sikh Philosophy Network http://www.sikhphilosophy.net/hard-talk/8793-guru-granth-sahib-ji.html
As per Sau Sakhi we have way of baptism as dipping the corner of cloath covering Darbar Sahib in water and let is be drank as Charan Pahil beforre we had Khande Bate da pahil.
Reference:: Sikh Philosophy Network http://www.sikhphilosophy.net/showthread.php?t=8793
In Sarbloh Granth Guru tells 12 forms ie Ten Gurus ,Guru Panth Khalsa and Guru Granth Sahib.
So as er tradtion of Hajur Sahib Tilak was givne to Guru was symoblic but Panth was also givne Tilak of Saffron.
Tilak of safron is not from Hinduism as no one uses it and various Sanatan Sects have differnt Tilaks.