In the case of discrepancy in the Salah timings between those on Islamic Apps (like Athan for example) vs local masjid, which should be followed? Not as much an issue for regular salah as the congregation prayers line up, but for suhoor/iftar, it creates a bit of a margin difference ranging 10-15 minutes. Please advise.
Fasting start time is not pegged with certain Masjid’s time table. Instead, Allah has stipulated the start time to be Subh Sadiq. In our experience and research thus far, Subh Sadiq corresponds with the calculations when sun goes 18° below the horizon. Our Salah times at ilmHub & Darul Iftaa strictly follow 18° calculation for fajr. This will continue until we do our own observation to establish another opinion, or receive an equally viable research to the contrary.
Keeping the above information in mind, one should stop eating suhoor before the times on our calendar. If one gets delayed, then the only buffer time is 5 minutes (imsaak), which we indicate on our table. Beyond this time, one would have eaten within the Fajr time invalidating their fast.