On Profile table, we need to roll up the Min(values), but only display date/time past NOW.
If now date/time is 19/2/2022 4:45om the correct answer needs to be: 20/2/2022 4:57pm
In your Availability table, have a formula field that calculates if the date/time is after NOW.
IS_AFTER( {date/time field}, NOW() )
Then in the Profile table have rollup that uses MIN(values) with a condition based on the formula field.
Note that NOW only updates every 5 minutes to two+ hours. So it is almost always behind. If you date/times are always on different days, this probably won’t be a problem.