Hi, so sorry to hear about your diagnosis. The diagnosis can feel like such a shock followed by the news of side effects. I think the main thing to do is consider what is right for you. Personally I got a short haircut immediately ( like a short bob) and chose a wig. After my first round of chemo it started falling out so I cut it short. Then after my second I shaved it as more was falling out. I wore “fashion turbans” after this which made me feel good. I never actually wore my wig.
Others I met either shaved their hair immediately and left it as that or cut it short and got a wig. I’ve seen people online go for one final crazy hairstyle they always wanted to try or a wild colour. 

It’s certainly a journey and at this point people saying it will grow back feels so far away. It was strangely a relief after my hair fell out as I had been dreading it and then I didn’t have to worry about it anymore. 
A lady at the beginning of my treatment told me hair grows back better :) mine is now long, thick and a totally different colour than before. Good luck with your journey and there’s plenty of people on here who can relate and offer advice or a listening ear.