My baby was born with flat head (plagiocephaly) on his left back side, and my nurse and I repositioned him from Day 3. We tried the logroll, or rolling up a towel for when he was in pram or bouncy seat. Nothing improved it, his head was still flat. So, at 5 months we saw a pediatric plastic surgeon and ordered a helmet from DocBand in America, after everyone, even doctors said, "what are you worrying about, ther'es no problem?" Even the London plastic surgeon was indifferent about putting him in it. Friends and doctors, even hubbie thought I was overreacting, yet he scored in the severe range for plagiocephaly. (the lowest numeral for severe but still.) See, I knew I wasn't crazy.
Now he's just out of his helmet after wearing it 2.5 months (he outgrew it), and I am still not 100% happy with roundness, though he is almost in the range of normal, and the helmet technician thinks he looks great. I am going to have him measured again to see if we need a second helmet, after about 3 more weeks. Bottom line, it's up to you the parent. Do not listen to any friends or experts. Helmet has done miracles towards improving his condition, but many babies do go into a 2nd helmet b/c it cannot guarantee perfection.
They have to wear it for 23 hours a day, but it's for such a short time in the scheme of things. Best is to have babe in it by 6 months old, but even as late as 14 months will get some improvement. BTW, my insurance company paid for it.
Loads of babies with weird heads around b/c mommies do not know, or do not think it's "that bad". Well, if you asked on mumsnet, then you must be concerned. I feel really sorry for some of the babies I know who's mothers do not seem to get it.
BTW, harder for boys, b/c they cannot "hide" their weird flat heads with back combing and hairspray like girls.
That being said, I do have a good friend who's DS had it 4 years ago, but they couldnt' find a helmet doctor in London b/c it didn't exist then. They ended up just repositioning and taking their chances. Well, their son now has a beautiful head. Lucky him. But, who knows? We just thought with all the repostioning we did, our baby coudlnt' get there on his own.
Good luck, it's a tough decision, but there is nothing lost by going to a plastic surgeon. Then you'll know.