Hi there,
They all are different really. If your setup is up to par I wouldn't worry too much.
One of mine basically didnt eat for a week. And on week two be slowly started eating a bit. And it wasn't until week 3 where he really started to eat good.
And then I've had others who only took a few days to a week. And some like you who ate from day one.
Just keep a salad in their for them and keep offering feeders. Eventually they will come around
-Brandon