Weaning before 6 months is a bad idea unless recommended by a HCP for medical reasons (weight loss, reflux etc).
Why are you shocked Fartness? Being 6 months old, plus having other signs of readiness is what is advised. So the stomach is mature enough, and they can actually sit up. Not whatever comes first. 4 months may not have been considered early 20 odd years ago, but now it is because as with most things, research has found problems with it.
Op
Sounds like you did it just for the sake of it, your baby isn't bored, and only needs milk. Milk is the only thing a baby needs until 12 months. 6 months is when it is advised that you begin to introduce food, and even then it's not vital for nutrition for a long while. He doesn't need to 'go' longer between feeds. They can feed on demand, or put an extra ounce or two of milk in the bottles to test their hunger.
Baby rice has nothing nutritional in it, it's just a filler. But if the baby is feeding well, sleeping well, gaining weight, why would you need it? If you really insist on doing it, purée fresh fruit and veg mixed with a little milk. Even that is completely unnecessary at this stage but at least it would be good food.
Their stomachs aren't ready for solid food this soon, research shows that conditions like IBS, IBD, Crohn's and other stomach and bowel conditions may well have been caused by early weaning in some cases.
You say you aren't a fan of BLW? As a first time parent who "can't be arsed to sit and research stuff" you can't be that clued up? It is strictly only intended for babies 6 months and above who can sit up properly in a high chair to eat. Really, weaning at any age shouldn't be considered until the baby can sit up straight in a high chair because of a choking risk. Feeding purée doesn't eliminate the choking risk, in fact it's just as dangerous when you are doing it with such a young baby who I doubt can sit up yet. Look up Millie's Trust. This is in memory of a little girl who was 9 months old and was fed mashed potato by a nursery worker. She was way above weaning age, able to sit up, and she choked on a very soft food.
Maybe you should do some research after all?
In addition, I would be so upset if my DH decided to start something like early weaning without speaking to me first. Not only because of the health risks but because it's a big step and most parents would want to see those first tastes and reactions. How would you feel if your husband took away your say, and seeing it all from you.