As Salaamu Alaikum Respected Mufti
I am jointly responsible for making Athaan and Iqama at our local Masjied.
In winter we have a 10min delay before starting our Fajr solaah as we have lots of people not from our area, performing solaah and heading off to work immediately thereafter.
In summer we extend the delay to 15min due to it being so early and its mostly the local musallahs.
This particular Fajr morning I decided to wait an additional 15mins in the hope that the Imaam would show. I personally knew everyone present, no outsiders were present, and made a call to wait, as I knew most of the locals would be heading back home to sleep anyways.
Eventually, we started solaah 30mins after the athaan had sounded.
Afterwards, I was informed that if the notice board indicates 15mins before iqamah, then we should stick to this as this is an appointment we have made with ALLAH SWT himself.
I was also informed that our beloved Prophet SAW, never delayed the salaah for Fajr and for Maghrieb especially.
My only reply was that I saw nothing wrong, as long as the solaah was made in its time and seeing that the salaah was so sparsely attended, to wait a little for more musallahs to join us.
Please assist in this regard.