Hi there
Zac took a while to take to the HAB. He too has a strong little neck etc.
I first tried to use it whilst he was unsettled. No luck.
I started to use it in very small doses shortly after his feeds. DH also used it too.
He slowly got used to it and now drops off to sleep every time we pop him in!
Might be worth evaluating what you and he are wearing, I know Zac gets hot very easily in it so we have to go a layer lighter, I suspect his temperature had a bearing on how well he settled initially, he was getting v hot.
Good luck it is worth perservering a little longer.
Belinda