Capital gains on selling flat pre/post April 2020

Hi

I have a flat which is currently rented and I am considering selling it. I am trying to work out timings and if I sell now whilst Brexit is going or after when the market is a little happier but possibly after tax changes. I just did some calculations and it seems the changes to the lettings relief will sting me but I want to make sure I have got my calculations correct. Details are:

Bought in Feb 2009 for £125k. Current market value £250k.
As of 5th April 2020 I will have lived in it for 40 months in the 10 years or so I have owned it.

If I sell 4th April 2020:
PRR: £58,468 58 months (40 months lived plus 18 month relief)
Letting relief: £40k
Sale fees: £3k
CG allowance: £12k
Tax due on: £11,532 and at £28% it is £3,229.

If I sell 6th April 2020:
PRR: £49,395 49 months (40 months lived plus 9 months relief)
Letting relief: £0
Sale fees: £3k
CG allowance: £12k
Tax due on: £49,395 and at £28% it is £16,969.35.

Do these figures look correct?

Thanks in advance for any help.