Trolling aside, the current meta allows healers to do a fair amount of damage, as opposed to last expansion where it was pretty much Disc and MW. But the majority of fights will have some form of healable damage within the first 25 seconds so your pot isn't wasted, but if there really isn't then there's no harm in DPSing for the first 20 seconds.
Good thing OP is looking for a "high standards" raiding guild where potting is the norm, if you opened your narrow viewpoint you'd see how much of a regularity it is to pre-pot even in below average raiding guilds.