Of course I've never take my own advice, but I wanted to share these pictures to hopefully stop anyone becoming too disheartened when they test early (and to hopefully help them avoid testing too early)
These were all taken with super-drug pink dye tests.
I have also included an inverted image in case anyone does invert to show what they looked like when I tweaked them.
As you can see, my line was barely noticeable before my period was due and very faint on the day of my missed period. It only really darkened a few days after I missed my period.
So for the love of God... put. The. Pissy. Sticks. DOWN 
Good luck everyone- I hope this provides some reassurance to anyone who is asking google about very faint positives/ testing early and for reassurance from their test