Only have anecdotal information about West Africa, but my family & friends have said that in Ghana & Nigeria - people who flew into the international airports were being screened for high temperature/fever as early as February.
For Ghana specifically, the government placed international travellers into enforced quarantine for 14 days at various hotels, and tested them at some point in the last 2 weeks of March (my mum landed March 14 and didn't have to quarantine). If I remember correctly, as of end of March, there were about 150 cases, approx 2/3 of them were from those in the hotels, and the remaining third came from the general Ghanaian public.
The country then went in lockdown at the start of April, stopped all flights & closed the borders with about 200 reported cases - as of now there are about 900 cases that have been reported and so far about 10 deaths so they're definitely on the uphill part of their peak, but i'm hoping the death rate continues to remain low.
Whether those numbers are 100% accurate is a separate discussion, I don't think any country is reporting accurate numbers right now - but certainly the Ghanaian Government has been very proactive, and because of their early action while the numbers were low - they've certainly saved a lot of lives.
I have a theory on why I think the death rate is so low, but this isn't the thread for that and don't think it's appropriate right now anyway.