Spell out the time of day when it is on a quarter hour or half hour.
He gets up at six thirty every morning.

Spell out the time when using o’clock.
The meeting is at seven o’clock.

Use numerals when an exact time is being emphasized.
The flight leaves at 8:23.

Use numerals when using a.m. or p.m.
The ceremony will be at 7:00 p.m. on Thursday.

Use noon and midnight instead of 12:00 a.m. or 12:00 p.m.
The luncheon will be at noon on Friday.

 My first post to this blog was on June 19, 2009. Today starts a new year for this blog.

I find these posts beneficial. They have provided me with an education and a reference. Hopefully they have been helpful to others. I am surprised that I have been able to come up with grammar information for this long. It will be interesting to see how much longer this goes.

 Here is a list of all the anniversary terms:
1 year             Annual
2 years           Biennial
3 years           Triennial
4 years           Quadrennial
5 years           Quinquennial
6 years           Sexennial
7 years           Septennial
8 years           Octennial
9 years           Novennial
10 years         Decennial
11 years         Undecennial
12 years         Duodecennial
13 years         Tredecennial
14 years         Quattuordecennial
15 years         Quindecennial
20 years         Vigintennial
50 years         Semicentennial
75 years         Dodranscentennial
100 years       Centennial
125 years       Quasquicentennial
150 years       Sesquicentennial
175 years       Dodransbicentennial
200 years       Bicentennial
250 years       Sestercentennial
300 years       Tercentennial
350 years       Sesquarcentennial
400 years       Quadricentennial
500 years       Quincentennial
600 years       Sexcentennial
700 years       Septicentennial
800 years       Octocentennial
900 years       Nonacentennial
1000 years     Millennial
2000 years     Bimillennial
Taken from Wikipedia (anniversary)

See this previous post for anniversaries less than a year.