Two and a half to three minutes in total for 15 g of coffee. But time is not a goal in itself: it is the easiest read on whether your grind is right.
If the brew finished under two minutes, water raced through the bed: the grind is too coarse and the cup is probably sour. If it ran past three and a half, the bed choked: the grind is too fine and the cup is bitter and drying.
Pouring slowly to hit a number on the timer stretches the brew without solving anything. If the time is wrong, the thing to change is the grind.
Pouring twice the weight of the coffee and waiting 30–45 seconds is part of the total. That pause is there to let fresh coffee release its gas.
Three and a half to four minutes is normal for 30 g. There is no single number for everyone: find the time that works at your dose and repeat it.
Fix My Coffee records brew time as part of the brew, so you can see what happened at which timing.