I hope all is well. I have read the articles on purifying your wealth on the IFG website but I am still a bit confused. In regard to purification, how often should I do this? Say I have invested in Shariah-compliant stocks but I still have to purify 5% of my earnings, do I do this on a weekly basis? Or monthly, quarterly, annually? Also do I have to take out 5% from my savings account directly or can I calculate 5% of my earnings and donate via cash I have on hand?