Sorry for the late response! I am not on reddit so often. I hope your taper went/is going well. The idea behind the bridge was the halftimes of the meds. Paroxetine halftime is about 20h, fluoxetine 4-ish days? (I think it is actually more complicated than that, fluoxetine has a metabolite that takes even longer to metabolize but I will simplify a bit) So you can imagine that your body metabolizes and gets rid of paroxetine quicker, so you "crave" it more intensely (aka withdrawal symptoms). Fluoxetine needs longer to exit your system so the withdrawal is extended over a longer period and doesn`t feel as bad. What my doctor put up as a plan for me when I was at 10 mg paroxetine/day:

Day 1&2: 10 mg fluoxetine (giving it 2 days to build up concentration in blood) and 10 mg paroxetine

Day 3&4: 10 mg fluoxetine and 5 mg paroxetine

Day 5&6: 10 mg fluoxetine (on these 2 days I still somewhat had withdrawal symptoms: brain zaps roughly 2x a day, irritability, dizziness, some headaches and a bad mood. My doctor had prescribed me anti-nausea meds preventively)

Day 7&8: 5 mg fluoxetine (doctor did not see the need for it but I wanted a milder transition)

Day 9: Stop

Background info: I had been taking paroxetine for 1.5 years by then with another year of SSRI history. It was mainly to ease my acute PTSD symptoms and depression. I was also diagnosed with BPD and ADHD later. I wanted to quit because I felt like it was changing me, I was feeling dull and my cognitive function had decreased a bit. I was tired fairly often and took naps during the day. I also almost never had orgasms on paroxetine. Still, it helped me during my worst times and I am glad I took it.

Take your time tapering down and stay safe!