If

These are both OK. The second is less direct.

Will it be okay if I send a message now?
Would it be okay if I sent a message now?

JesterLegacywhen do we use a past tense and present tense after the the word "if"?

Usually you use the present if it's realistic to expect that the action of the if-clause might really occur.

Use the past if you are just musing about some possibility that may or may not occur — if you're just doing "armchair philosophy" — imagining a situation.

Then, what if there is a scenario such as: My friend didn't attend a meeting last week, so he asked me about something regarding the outcome of that meeting.

Is it okay for me to say: If you had attended the meeting last week, you would have known?

JesterLegacyIs it okay for me to say: If you had attended the meeting last week, you would have known?

Yes. That's a counterfactual past.

CJ