I really appreciate your question and I understand the difficulty of knowing the timing in how we are to represent Christ in each situation. I agree with @SeanO that there is not a one size fits all way to go about witnessing to others. I would like to just add a few points that I have learnt in also considering this question:
One of the first things that God came to reveal to me is that He doesn’t ‘need’ me to witness my faith to others in order for people to be saved. What I mean by this is that God is more than capable and powerful enough to bring people into His saving grace without me. It is true that God seems to predominantly use people to lead others into a relationship with Him, but it is a mistake to think that God needs me to witness so that He can now save people. The reason this was an important revelation in my life is that it took the burden of salvation off of me and onto Him! I used to always be around people or work colleagues trying to figure out how I can witness or how I can try and start a conversation about God. I always felt pressure and awkward because it became difficult to relax in the conversation and was more constructed then flowing. As soon as I gave it into God’s hands and told Him that I desire to be an available servant to His plans, it released so much pressure on my life. The amazing thing was that all of a sudden conversations started opening up naturally, which I didn’t even do anything to start. And there was freedom and peace within the conversations because they flowed out of me just speaking as me, which I believed was because of the Lord’s anointing over the conversation.
Another point I would like to add is that Jesus met peoples needs where they were at. When blind and sick people came to Jesus and asked for healing, He didn’t first give them a sermon on how to be saved. He met people where they were at. He showed and gave the love that they needed at that time. Meet your friend where she is, love her as she needs to be loved. If you are not sure how to do that, then ask God for wisdom, or ask your friend, if you feel comfortable, how you can best love her now. You will be amazed at the opportunities and conversations God is able to open by loving people by meeting needs.
Lastly, something I have done is give books to people which I felt that they may enjoy reading, that can open up spiritual conversation or reflection in the persons life. My nieces name is Betsie, and she was named after Corrie ten Booms sister, who I read about in the book “The Hiding Place”. I have recommended the book and given the book to a number of people who were just interested in where the name came from. It didn’t matter if a conversation started or not from the reading of the book, it was given because it may plant spiritual seed within that person and hopefully they would find it interesting. I left it in the Lord’s hands.
That is just some thoughts that I hope may help you Olivia in seeking how to best witness your faith to friends or family. There are many others on this site who will be able to hopefully help you with your questions .