I have used hour old sperm and although I didn't get pregnant I still think it's okay.
I've copied this from a donation site
A common question often asked by sperm donors and their recipients
is: How long do sperm live after ejaculation? This question is not a
simple one to answer as the biology of a living sperm is complex.
Theres been a lot of misinformation published on this question on
several websites.
Some people have said semen lives about two
hours after ejaculation, and starts dying immediately after ejaculation.
Others have said that the container of sperm should be kept at body
temperature, ideally close to the human body in a bra. These
answers are, at best, not very accurate.
Heres a more accurate answer to the question. To understand how
long a semen sample will live, its necessary to think in terms of the
biology of a single, healthy, sperm. When a sperm is first ejaculated, it
contains a power pack of chemical energy. You can think of this
power pack as a mini (AA-type) battery. As the sperm swims around,
the batterys power is used up like petrol/diesel is used in a car.
Once the battery has been fully discharged, the sperm can swim no
further and dies. If a sperm is relatively cold, say around 12 degC, it
wont swim much so the battery is conserved and the sperm will
survive for quite a while. If a sperm is at body temperature (38 degC)
itll swim around a lot, and the battery wont last very long perhaps
2-3 hours maximum. At room temperature (22 degC) a sperm will
swim a bit, but not a huge amount, and its battery may last up to 8
hours. So theres no simple answer to how long a sperm will live after
ejaculation. Your best bet is probably to keep the semen sample at
room temperature and inject it within two hours of its ejaculation. Here
are some hard facts:
· If a semen sample becomes very hot (above body
temperature at 38 degC) the sperm wont live long at all less
than one hour.
· If a semen sample becomes very cold and freezes solid, the
entire sample can be considered dead. The same is true, of
course, if the sample dries out. Sperm donor clinics are able
to freeze sperm because their samples are mixed with an antifreeze
agent (called a cryoprotectant).
· Its not at all necessary (or a good idea) to keep a semen
sample at body temperature for the sample to survive after
ejaculation. Body temperature is an ideal swimming
temperature for a sperm, so keeping a sample at this
temperature will exhaust the sperm pretty quickly.
· One of the main factors influencing the potency of a sample is
sperm count. This varies a lot between sperm donors chain
to you, hope you have a good 2 week wait 
