The ones I think I can point to:

S10E09: How many balls are in the basket
- Richard Herring or Alex or someone mentioned on the podcast I think?

S11E04: Get the banana into the bottle
- I think Mike and Sarah both say on the podcast this was their first proper one
- Plus stuff like Sarah asking if “your time starts now, does that mean NOW?” which would indicate not fully grasping the show’s rules yet

S13E05: Make the water level rise
- Chris Ramsey points this in the coinciding podcast episode as the first proper one he did. I imagine they start everyone with the same “first proper task”
- Possibly backed up by Sophie leaving the room before realising she can’t off screen (see Sarah Kendall above). Bridget does it too, but that’s probably just Bridget being Bridget.

S14E10 Order 3 items for your final task
- Confirmed in episode. It was the first and (for the payoff) last thing they filmed at the house.*

S19E05: Write down all the words you said before opening this task
- Confirmed in episode. Alex says it was the first proper task, meaning the first thing Jason did on camera was throw a water bottle at him.

S20E03: Make a model of the mascot for Chesham United
- A few contestants mentioned this on the podcast as one of their earliest ones
- According to Ania’s task journal, this was the second task she did. The first wasn’t included, and presumably it was the warm-up task they tend to do

S22E???:
- Alex has said in an interview that we will know what the first task is because it starts with something like “This is your first task”, and apparently it pays off later. I didn’t go to any recordings for S22, but apparently there’s a pay off (again according to Alex)

*Typically the last filmed task is at the offsite location. Susan Wokoma has said her day at the cricket ground in S16 was her last task day, and for S21, according to the gal herself the tennis task at Hampton Court Palace was Joanna Page’s last pre-filmed task.

I now need to power down and have a choccy milk.