In my opinion, you don't have to use kanji before you understand which kanji is correct, when you should use them because the same pronunciation has several kanji, sometimes many kanji, but the meaning is different. Using wrong kanji is worse than not using them. You can learn naturally step by step, from the basic kanji or very common ones like "I", "friend", "dog", etc. I'd like recommend you to add the English sentence if you start writing "notebook entry" here. Please do not worry about it too much and enjoy learning. Good luck!