Rabbits Introducing Rabbit food.

@Gandalf @Inle_Rabbit

I wouldn't worry too much about the pelleted food. I have never had a rabbit have stomach issues from a pellet switch. I would introduce greens slowly, one green at a time until you build up to the recommended amount for your future rabbit's age and weight. Remmeber to have a grass hay available 24/7 for the rabbit.

I give both my guinea pigs and rabbit two meals of veggies. One in the morning and one in the evening. I give them their pellets in the morning and I make sure their hay is refilled at both feeding times. All the animals get food throughout the day though from the kids. Usually it is carrots and lettuce leaves from the kids.

Some rabbits can have issues when switching pellet brands. Some simply refuse the new kind. I've had rabbits that transitioned without a problem but I've heard stories otherwise on my rabbit forum. When you get your rabbit from the rescue, they should give you a few days worth of the pellets they've been feeding him. You can use those pellets to mix with whatever pellet you have chosen. The usual suggestion is to mix 1 part new to 3 parts old for a few days. Then switch to an even mix - half and half. Then mix 1 part old to 3 parts new. By the end of a week or so, bunny will (should) be used to the new brand. It certainly won't do any harm to use the transition method.

Inle's suggestion for the greens is also what I would suggest. You could also ask the rescue if/how often their rabbits get greens. Skip fruit until bunny is good and settled. It is just a treat anyway. You could also take a peek at my site that goes over the feeding of greens.

As for when to feed pellets, or greens, etc. it is really up to you. Rabbits are creatures of habit and they will come to expect things at certain times once it becomes habit.
I refresh hay every morning and evening (and sometimes during the day). I feed greens just once per day -- around our dinner time when I'm in the kitchen anyway.
They sometimes get a treat in the evening when we are all in the family room. Then I feed the pellets directly before I go to bed. The reason I do this, is that my rabbits are free range all day. The pellets are the bribe that gets them scurrying back to their cage for the night.