A)as because it's used to connect the dependent clause to the independent clause (as is also one of the most popular subordinating conjunctions)
You woke up ate breakfast went on your console or pc then ate lunch then you played on your phone and then ate dinner played more on your phone or console/pc then went on your bed watched some tiktoks and went to bed
Two things to keep in mind when you're deciding whether to use formal or informal English are the B) occasion and the audience.
Of course you are going to change the way you talk depending on whether you are speaking to your friends or to your teacher - usually with the teacher you are going to use more formal English.
Occasion is also important - you won't speak in the same manner at a party and a cocktail.
