Didn't seem to hurt Apple with their first products ...

I'm pretty certain that marketers wouldn't go for a 'me too, I'm trying to copy you' branding and would point out to anyone who thinks that 'j' is good idea that the 'i' in iPad, iPhone etc doesn't stand for Apple - it is a clever bit of branding, that simply sticking the first letter of the company name in front of a product cannot match. At all. Basically jPhone is non-starter.

Should Samsung phones really be sPhones? Or HTC phone hPhones? Or LG phone be lPhones? That certainly seems to be what you are suggesting.