I think there is a critical time when you need to introduce a teat or you run the risk of them not taking a bottle (easily).
I also think it is quite early on too. I.e between 0-8 weeks.
I don't think the health professionals are upfront about this either. I had the message of 'don't give dummies/bottles as it will cause nipple confusion' instilled into me and I was very determined to breastfeed so I avoided them.
I did want to express though so my partner could help out. And also because I did not want to be held hostage by the baby. So I started after a about 7 weeks.
I had many many stressful times trying to get my LO to take a bottle. It almost broke me tbh. She would scream and scream and scream and I would give in and breast feed her. I tried all different teats and bottles and persisted and eventually she did take it.
During that time, I used to think 'what if something happened to me? How will the baby survive?' I come to the conclusion that she wouldn't have starved herself to death and would eventually take it, which I think it probably true for almost all babies. Though if the baby is a bit older and used to bf, the. to get that that point can be very distressing for both of you. I guess what I'm trying to say is, it probably not impossible to introduce a bottle but it will be a tough process if the baby has been solely bf for an extended period.
I have many friends who were in the same situation.