New car seat = screaming toddl

[doll]

I have just bought my little boy the next stage car seat. So he's now in the forward facing. He likes sitting in it except when the car sets off he screams and screams. He's so terrified bless him because he's so used to the rear facing seat. I know its not just a tantrum and he's really scared. Any suggestions for the best way to get him used to it??? I'm expecting my second baby soon and really need him to get used to it so i can use the other one for the new baby.

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toddler car seats