Is it normal to have different flowering times on ...

Hello ! It's perfectly normal , most strains out there have different phenotypes so you can find seeds from the same lineage that grow different each from another. For example a cross between a sativa and an indica can give you a plant that flower fast like the indica and with low height, another can give you a tall long flowering plant , and the 3rd can be a perfect mix of both and you can have many variation from the same strain. Most of the F1 are like that : many phenotypes. The best way to avoid that kind of phenomenon is to buy a strain that have been cross by cubbing ( 4 backcross with the same mother plant ). I hope it help you to understand your variations 😁👍