Why will a car start only on the 2nd attempt if its been off more than 30 minutes?

Not knowing the year or if carb or injected ill answer both ways Carb, it is because when a car shuts off the few revolutions it makes before a full stop draws some fuel into cyl so restart takes no more fuel, after a short period the gas evaperates so need to pump pedal to start. Injected ( MPI , TBI ) It means the fuel system is leaking down pressure, this can be the fuel pump itself or can be the pressure regulator that holds pressure on return side on shut down. The reason it starts on second crank and not first is that first crank gets pressure back up( pump only runs few a few seconds at start Even if cranked for 60 seconds pump wont restat till engine starts ) then second crank accually gets fuel in cyl. You can get it primed by turning key on for 5 seconds ( NOT to start mode just so lights and such come on) turn off for 5 seconds then Start it. This will be like the second cranking when starts.