Wrong amount of yeast?

I made my first all grain brew yesterday. It's larger with a final fermenter volume of 23l.
I'm using a Grainfather so all went well, kinda.
It looks like I got the amount of yeast wrong.
I entered a single vile of White Labs WLP838 larger yeast and some how missed the whole yeast starter bit.
I started fermentation yesterday around 6pm.
Can I just add more yeast today or is my brew doomed or do I just leave it to ferment longer.

When fresh, a single dose from White Labs has sufficient cells to ferment 19 liters. You're fine at 23.

The amount of yeast doesn't change the speed of fermentation as much as temperature or oxygenation, but yes, it can take a little longer. Low pitches can have elevated esters and take an extra day to get started, but this is not cause for alarm.

That's good to hear.
I will relax and be patient.
Thanks