At an or at ?

[james_chew_84]

Please have your meal at an appropriate time?
or
Please have your meal at appropriate time?


Thank you.

[Casiopea]

Please have your meal at an appropriate time?
or
Please have your meal at appropriate time?
Thank you.

The first one, an appropriate time, is correct. 'time' is a count noun in that context. For example,

You should eat at a time that is appropriate.
You should eat at times that are appropriate.