I take the parable of the sower to be a picture of what happens after baptism. Some never even got the idea. Others dry up when the going gets tough. Others get choked by cares and worries. But, and this is the important thing, some go on to be very very fruitful.
I only think a serious step should involve serious thought beforehand if the step could be dangerous. It is not dangerous to open one's first bank account, so it can be done instantly. It is dangerous to buy a big house with a large mortgage, so that needs thought. But there is nothing dangerous in beginning to learn from Jesus.
Everything depends on the way we use the word Christian. Some think of it culturally, e.g. belonging to the Christian community as opposed to the Jewish, or Muslim, Buddhist or Shinto community. That kind of change would take a lot of thought.
But there is no contradiction in being Arab by birth and Muslim by cultural community, or Japanese by birth and belonging to a Buddhist or Shinto family, and at the same time learning from anyone one chooses. Think of your son enrolling in his first Judo class. At that point he does not have to count the cost of going through to a black belt.
Simon Peter was a Jew, after enrolling by baptism as a disciple of Jesus it took him three years to make the confession in Matthew 16:16. But he never really broke with orthodox Judaism until he ate non-kosher food (Acts 10:14-15, 11:7-12).
The only definition of Christians in the NT is in Acts 11:26
where the term Christian was applied to disciples or learners. And every
baptism in the NT is immediate without time to do much thinking through
of implications. There is no risk at the point of baptism (unless governments
or religious authorities make it illegal), but the cost and the joy of
living out what one learns is likely to be more than one expected.