Close the tab and, if you can hold the itch to gamble, wait 48 hours.
Push Gaming bonuses saves for 48h.
After that it just auto pays you the result of the bonus and you can check it on bets feed (and on your balance, of course).
Definitely the activity within the last 30 days, but it's not only wager that counts towards the amount you'll get.
I guess the most important variable is how much you are up or down in those 30 days of activity.
Even if your wager is not high but you lost too much money, you'll get a higher monthly than someone with a high wager but in profit on the month.