I started DD1 at 4 months and DD2 (who is almost 6 months) about 2 weeks ago. Honestly, the timing really had to do with the randomness of when we had their 4 month pediatrician visit scheduled and I got the "green light". Agree with Martina about there not really being any rush, unless you think bc of your LO's size, he seems hungry.
With DD2, I also did pears first. Honestly though, I don't think it really matters, because now 3 weeks into it, she is having 5 or 6 different things, fruits and veggies both. And while she shows definate preferences (sweet potato, pears, apples), she will eat veggies too.
I was advised by DD1's Ped to start with the least tasty foods (veggies) and then move up to fruits, lest they reject the veggies at a later point (at least the puress). Honestly though, I think that is giving them too much credit. They only have rudimentary taste buds at this point. Moreover, my DD1 hated those nasty pea and green bean purees, but has loved fresh veggies since she was a toddler. I do not think there is a correlation.