When can I test?

Rachelle • 🇬🇧 Endo and ttc #1

So I have a 26 day cycle but glow has it down as a 28 day cycle for whatever reason. I'm currently 4 DPO and due to start AF in 8 days (according to my calculations) so when do you lovely ladies advice I start testing? I'm really hoping this is my month as it's the last one before I start <a href="https://glowing.com/glow-fertility-program">IVF</a>.

That's my calendar and I've circled when I think I'm going to start AF. Thanks in advance!