When can I use my FRER?

I know im only a few days dpo for now but my cycles have been mad short since i got off nexplanon.

Clue says I'm due on the 12th... but it also said i was due on christmas eve.

Glow says I'm due on the 16th... but the cycle days go from 23 to 28.

i dont know what to trust!

i only have one single test at home so i wanna make the most of it. i know the obvious answer is BUY MORE DUMMY but its been pouring all weekend and probably will all week long as well, roads are flooded, highway is slippery, people drive like lunatics. so i reeeeeally dont wanna leave the house til the weather takes a chill pill (literally... its too damn hot for january)

should i take it on the 7th? should i wait til the 11th? should i find something more sensible to occupy my time/dostract myself with?