To be honest, he does look older than 4 weeks to me. I would put him in the bracket of 6-8 weeks, personally. I would put his breed at dwarf fuzzy lop.
But that aside, weaning early and feeding veggies early can cause major problems for a rabbits digestive track. Theres also the fact daily fruit for rabbits can cause stomach problems as well as obesity (they gain weight very quickly on sugary foods, and fruit is all sugar) very quickly. One small piece of fruit should be a once a week treat at most. This is why everyone is telling you to slow down. Youre risking your rabbits health by moving way too quickly with their diet.
Start with alfalfa hay and pellets until your rabbit is six months old. At six months, you can start to wean over to timothy hay and pellets, as well as start slowly introducing greens.
Side story: We bought our Bombur at 3-4 weeks old. The breeder lied to the store we bought him from (the store no longer takes in babies from that breeder after we told them). For the first week or two I had to syringe feed him every few hours because he didnt know how to eat hay. He would eat his alfalfa pellets throughout the day (what the breeder weaned him onto), but would only nibble on hay on and off with a confused expression. With an “okay” from our vet after talking to her about everything and learning his real age, we weaned him off of syringe feeding and onto hay relatively early (4-5 weeks old). She said since the breeder weaned him onto pellets and removed milk from his diet super early, it wouldnt make a difference if I kept on pseudo milk or completely transitioned him to hay. In a sense, the damage was already done and not really reversible since the breeder weaned the litter so early. Putting him back onto pseudo milk wasnt going to make a difference. If I had the mothers milk, it would be different, but that obviously wasnt an option. Of course, also noted by the vet not to add veggies till six months, as thats the proper age for any rabbit to start introducing veggies and greens. Obviously, we waited on that.
Several blood and gut tests later, Bombur has been diagnosed with a sensitive tummy. In that, meaning, he is prone to gas build up with you stray from his diet. Trying new veggies or types of hay are often met with belly massages several times a day as well as gas drops. On the off chance new veggies or hay works well with his tummy, it needs to be added in suuuuper slowly (Im talking over the course of atleast two months). It will be like this for the rest of his life, and only get worse as he gets older. Weve been lucky not to fall into stasis with him, but as he gets older, it is only a matter of time. All of this because he was weaned too early by the breeder.
I say this because I understand where youre coming from. You were given a bunny who was weaned early by no choice of your own. That is the store and breeders fault, not yours. But, by choosing to further his diet change because you were given incorrect information at first, knowing now that it is incorrect, is not acceptable. You need to slow down before your increases cause permanent damage to your bunny. Even if the early weaning already caused damage, you do not need to further cause damage by adding veggies to his diet way too early. You can stop feeding fruits and veggies without causing harm at this stage.
To side note, gas really hurts rabbits which is why many prone to gas and sensitive tummies end up in stasis. The rabbit will refuse to eat thinking eating is the problem causing their pain (to be fair, it is eating that causes the gas that causes the pain). Stasis can kill a rabbit within 48 hours if not immediately dealt with.
.
