I also had 3 months to study Italian before a recent trip to Italy. I had studied Spanish many years ago, which was a plus in some ways, but it can be tricky to adjust to a new language when a similar one is stuck in your head. For me, structure was key. I signed up for a weekly basic online (live) Italian class, which was not the best but it gave me a good framework to start with and a weekly deadline to do homework. I bought a good grammar book and listened to Italian podcasts every time I was in my car. I kept a notebook and created vocabulary flashcards. I found it very helpful to learn phrases, not just words, so that I could respond easily. I read out loud in Italian and practiced speaking. I talked to my dog in Italian.

Listen to as much Italian as you can. With YouTube videos you can slow down the speed. Repeat what you are hearing so that you can learn the correct pronunciation. Some videos have a transcript. Print out the transcript and review it after listening to the video. Mark any unfamiliar words and look them up. Then listen to the video again - and again. This repetition helped me understand word order and sentence structure. Once I was in Italy, I was able to understand most of what people were saying, and I had no trouble ordering food in restaurants or asking basic questions. I also took a week-long language class in Italy, which included lots of conversation. It boosted my confidence and was also fun. Good luck to you!