From the links provided in the referenced post, it seems like the authorities are likely to allow you passage even if you had the yellow fever stick the same day (or they would have to quarantine you for ten days if you received it on landing).
The issue is that, if you are arriving from a yellow fever area, such as Kenya, you may be asked for proof of vaccination to assure you are not bringing yellow fever into the country. And sometimes, it can be political - "Country A" imposes the requirement on "Country B" in retaliation of "Country B's" import duties on "Country A's" chickens, say.
The WHO, for example, states, in the International travel and health book, viewable or downloadable
here:
Code:
KENYA
Yellow fever
Country requirement: a yellow fever vaccination
certificate is required from travellers over 1 year
of age arriving from countries with risk of yellow
fever transmission.
Yellow fever vaccine recommendation: yes
Recommended for all travellers aged 9 months or
over, except as mentioned below.
Generally not recommended1 for travellers whose
itineraries are limited to the following areas:
the entire North Eastern Province; the states of
Kilifi, Kwale, Lamu, Malindi and Tanariver in the
Coastal Province; and the cities of Nairobi and
Mombasa (Map).
ZAMBIA
Yellow fever
Country requirement: no
Yellow fever vaccine recommendation: in general,
no
Generally not recommended1 for travellers going
to the following areas: the entire North West and
Western provinces
Not recommended in all other areas not listed
above.
For medical advice, I would go farther than FlyerTalk and go to the health authorities. For yellow fever, I always get my stick, every ten years, because I do not like surprises - e.g. arriving at a country with new requirements that may not have been published to the web yet.