Hi:) Usually it takes two to three days to completely understand and memorise all the hiragana letters. I recommend making little flashcards to test yourself with, that helped me a lot.Since you know mandarin, learning kanji would be slightly easier too. If you're looking for a friend to help you with the grammar and extra vocabulary part, feel free to send me messages:)

u can, baby n____n

To help me learn Hiragana I used an app called "Human Japanese". There is a free version and there is a version you have to pay for. On the free version I was able to learn all hiragana characters quite easily. On the paid version, from what I remember, it would teach you Katakana and possibly Kanji? I can't remember but all I know is: I learned Hiragana from that app and it came pretty easy. You might want to look into it and give it a try! Also when you say "Sayonara" you should use the "na" symbol な instead of "n" ん and "a" あ separately.

Ah yes, I've been watching some Japanese dramas and Japanese Youtube channels too!