The year can either be formulated as “twenty twenty-one” or “two thousand twenty-one.”
Grammar dictates omitting “and” in the year.
time
Time, like the date, is spelled out. To indicate the half hour, use the phrase “quarter after/until or “half after” rather than “quarter past” or “half past.”
The phrases “in the afternoon” or “in the evening” are not necessary but can be used if preferred.
“At” can precede the time or not.
location
State the venue where the ceremony will take place. Omit the address and the zip code, but include the city. Adding the state is optional, but should be spelled out if used.
reception
If the ceremony and reception are being held at the same venue, adding “reception to follow” or something similar under the venue on the invitation is not the most traditional option but is perfectly acceptable and fairly common, particularly for ceremonies held outside a place of worship.
If the reception is held at a different location than the ceremony or you simply prefer not to include “reception to follow” on the main invitation, a reception card is appropriate.
There are countless ways to word a reception card. A couple of examples: