Don't you need pronunciation training? Even some children learning their first language need speech therapy.

The key word is some. The majority of children acquire all the sounds of their native language perfectly without ever needing any kind of intervention. Even children that have a speech impediment have acquired all the other sounds of the language perfectly. Like most children, most adults won’t need any explicit instruction. Speech impediments generally only happen for very specific sounds that are objectively hard to produce, like the “s”, the Spanish “rr”, or the English “r”. As an adult, you should do the same thing that children do. Assume that everything will be okay and only seek help if something is not working. Once you get a few hundred hours of input to get used to the sounds of the language and after a few dozens of hours of speaking you'll be in a better spot to know if you need pronunciation training. The reason why trying to consciously learn pronunciation early on doesn't work is that the amount of different sounds that we can make with our mouths is unlimited. Because we use approximately 45 muscles when speaking, each basic sound in isolation is already impossible to completely convey with words. And to that you need to add:\n\nThe ways in which native speakers articulate the transition from one sound into the next.\nThe ways the sound changes depending on where the sound appears in a sentence.\nThe ways sounds change when one is speaking fast.\nChanges to sounds that depend on the situation, like social setting, the mood of the speaker, or relationship between the speakers.\n\nSince conscious study can't teach you all those things with precision, practicing speaking too early will result in getting used to your own idea of what the language should sound like, and not what it actually sounds like.