Do you make a case for compensation promotion/compensation before/during/after project in this case?

[severe surge]

My company just ended WFH which led to one of our se3 senior developers leaving. He, another dev (se2), and I (se1) have been working on a project for the last 3 months, a new product that will be owned by our team. It is in a framework I've never used before and I've mostly been doing low-level tasks to help out, trying to learn what I can. The project is starting to wind down to maintenance, but there are quite a few major tasks left. The se2 has started on a new project, and the understanding has been that the se3 would be finishing the rest of the work with me stepping in as necessary.

Now that he's left, I'm the person on the team who makes the most sense to head the project. It's understood that I'm new to this stack, and I am being given quite a bit of leniency on time considering that. However, I am having to juggle quite a bit, including finishing development and all deployment. I'm happy to do it, I like a challenge and I want to learn and grow, but I feel like I'm essentially doing the job that the se3 would have done and I think I more than meet the requirements for an se2 in my company. If pressure starts mounting on me and I'm stilling making my meager se1 salary, I might be inclined to look elsewhere.

However, I've never argued for a promotion/raise before. Would it make sense to do this before the project (as in before I'm fully the only one working on it), during the project (when I officially have all the duties), or after the project (when I've proven I could do it)?

One thing I'm afraid of doing is making them realize I shouldn't be the one doing it and finding someone else that's an se2 or se3 to do it. I don't want to pass on the project, I feel like I'm capable, but I feel like if they think I'm capable enough to take over this project then I should be recognized with the title.

[prime wraith]

It is very important to make leadership aware about your expectations. This helps keep everyone on the same page. So you will have to speak up. Unless you ask for it, you won't get it in most cases. There are standard professional ways to approach this.

Schedule a weekly 1:1 with you manager/team lead

Schedule a monthly 1:1 with your skip manager

in these 1:1s, let them know what you are working on, what challenges you are facing and how you are solving those challenges. This makes them aware about the importance of your work

Along with the work you are doing, tell your leads in 1:1s about the career trajectory you are expecting

This way you bring up the topic that you deserve a promotion or raise, as you are solving challenges beyond the scope of your current level