Section 21 notice period

Possession - Section 8 and Section 21

Hi Guys.
Having read the advice information, you state pre 31st March the notice period for a section 21 is 6 Months.
As we are now within two months of the 31st March, does this mean notices served now can give the standard 2 months notice ?
If not would the six months quoted on the sect 21 become reduced to the standard two months on the 1st April (assuming no further extensions are applied).
For Example a notice served today would under the existing rules state a leave date of say 22nd of August; or should it be :
a) Entered as the 22nd of April as its later than the 31st March; or
b) Entered as 22nd of August but defaults back to the 22nd April once the rules have changed; or
c) Wait until 01 April and submit with a leave date of 05 June.

This assumes the 31st March isn't extended in which case point C would move with it. The start date on the AST was 27 Nov 19 (so now a periodic) and rent payments are monthly.

I'm running this in tandem with a section 8 on grounds 14, but as that is discretionary I wanted a mandatory as backup.

I look forward to your feedback
Thanks Peter