Son has one offer from campus placements and wants to wait for a better company

Before he declines, check exactly what the rule says. Many colleges have a 'dream company' clause where a student with one offer can still sit for companies above a certain package. If his college has that, he may not need to choose at all. The placement cell will have the policy in writing. I'd read it rather than rely on what his batchmates say.

I can only speak from my nephew's experience. He took the first offer, a services company, and moved after eighteen months to the kind of company your son is hoping for. He says the first job taught him how offices work more than anything technical. It wasn't a wasted year and a half.

my son's a few years away from this. reading it, i keep thinking the part i'd find hardest is letting him make the call even if i'd make a different one

I interview freshers sometimes in my team. Honestly the company name on the first job matters less than people think. What we look at is what they built in their first year or two. A services job with real project work is fine. But if he's set on product companies, waiting is also not crazy, na. Depends on how strong his interview prep is and how he'll feel if the later companies don't come.

my brother took the first offer in 2009 and is still at the same company. not sure if thats a recommendation or a warning

Ours has just started college, so this is a few years off for us. When did your son start preparing for placements? Is it a final-year thing or does it need to start earlier?