How to Renegotiate Your SDR Salary After a Successful Probation Period at a SaaS Scale-Up

hey everyone, got a question I’d like your opinions on: i've been and SDR at a SaaS scale up for 4 months now (my first sales job) and i've been crushing it. i'm the top SDR, beating inbound too, and generated the most pipeline by far. my base salary is in the middle of the going rate in london. i have 2 months left of my probation. how do i know how much i can try and renegotiate for and what should i do if its declined. my package is a base + fixed fee per SQL (no percentage of deal value)