It takes an awful lot to build a human and involves 42 weeks of work, not to mention the 18+ years looking after it once it’s been built!
It takes just over a week to complete implantation but after only 3, important organs such as guts are already forming! After 9 weeks, there is sex differentiation and even eyelids start to appear and after 24 of the 42 week long process, any human currently being built has over 50% chance of surviving if born at any point onwards. So if you’re in a rush, it could be ok to finish a bit early.
Building a human is one of the trickiest tricks nature has to perform but thankfully, all we humans have to do is have sex for it to happen!