I started a new job two weeks ago using technologies that are new to me. I was upfront from the start about what I did and did not know so there's no surprises.
I do a little of everything and so I work with three project managers at one time due to the nature of my role being involved in almost every client project we have. When assigning me a task and allocating an expected time, two of the three project managers are generous with their time estimates and have mentioned that they understand I'm new and learning a lot of unfamiliar technologies while also trying to stay on top of multiple projects (which relate to the things that I'm learning). They give me enough time that I've hit the minimum time expected (or finish in less time).
But the third manager's project(s) are the most out of my field. Despite this, and unlike the other managers who are aware of how new I am, she repeatedly asks me "How long will this take you?" and when I reply, "I honestly couldn't give you an estimate because there is a lot of dependencies to get this task done that I need to learn first", her eyes bug out and I can tell she's trying her best not to lose it. I think the reason being is that the role I filled was backlogged with weeks, if not months, worth of work from the get go and so she's trying to hit deadlines for clients. She'll then assign me an expected time that, at this point, I've gone 10 hours over. I'm salary so it's not like they have to payout overtime and I also spend this extra time finishing up the project at home (going well beyond my 40 hours which is fine).
I don't mind busting my ass; I mind the sense of dread and emergency she approaches every conversation with because she's worried about the project timelines. It stresses me out and makes me feel uncomfortable for not giving her time estimates.
I may normally question my progress or capabilities, but I've had nothing but great feedback from the other managers. The senior project leader told me at the end of this week that she's, "Extremely glad to have [me]". The CTO even went out of my way to give positive comments on my work. So... How should I handle this?