if you mean when cold, it needs to crank longer before starting than it does when warm, it could be losing fuel pressure in the rails when it sits.
the next morning or whenever you feel it would fail, try cycling the key to ON - but NOT start - then wait 4-5 seconds, then back to OFF - then ON, wait 4-5 seconds. Each time you cycle to ON, the fuel pump should run for a few seconds, pressurizing the rails. After you do 4-5 of those cycles, start the car and monitor if it cranks more normally. If it does, you may have a fuel system problem. leaky injector, leaky cap/o-ring on fuel pump or ????