Symptoms started 6-7 days before positive test - isolation period?

[OUB1974]

At the beginning of last week (Mon), my son had a cough so we tested him (pcr) and as it was negative so we carried on as normal.

Later in the week (Wed) I tested positive (ltf) so I am isolating until the 5th. The whole family has been doing daily tests as advised by test and trace.

Son's has been negative all week but today got a positive. I filled in the info in the website and they say he only has to isolate until the 4th. This is because I put his cough started last week (which it did) so they have calculated from then, despite all of the negative tests. It doesn't seem right somehow. Has anyone else had symptoms start several days before a positive test?

Ds1 has just tested positive now, cold symptoms started Fri am but he was negative then and negative yesterday. So 2 days.

Knew he bloody had it.

If you choose go along with the earlier date, do LFD tests to make sure he's negative on the 3rd and 4th. If not, take today as his day zero and test him on days 5 & 6 from now (actually works out about the same time). He likely got a false negative on the first PCR, it's more common that people realise.

It’s correct. Day zero is the first day of symptoms. That is what the rules say and is what I’m doing with DD.