How am I doing with this introduction?

Hi there I just wanted some advice on when we should let these two actually be together.

I have our first cat Callie the 3yr calico (very original I know) she's a bit sassy and has been absolutely spoiled the last year-ish we've had her so bringing in a sister has been hard for her. Our new addition Krimpet the 2yr tabby is an absolute sweetheart and she's adjusted immediately after we brought her home 3 weeks ago. Krimpet is in the bedroom Callie has the rest of the apartment.

Now through this process we go onto every next step depending on how Callie is doing with the hissing/growling. Starting with scent swapping, room swapping, toy swapping, smelling each other under the door, paws under the door, and now we're at the letting them see each other through a screen door phase. It's taken a lot of treats and my boyfriend and I sleeping with each cat separately every night.

I'm gonna try and upload some videos of them at the door but it's a lot of ups and downs. Krimpet is very unphased by the growls and hisses from Callie. It can be a very sweet interaction where calling paws at the screen being sweet, laying down and just watching her or she pounces at Krimpet hissing/growling.

https://imgur.com/a/pq2iPki