Passed the first round of interview, submitted a task & was asked by the HR to provide the salary certificate which I provided yesterday morning but I didn't hear back since yesterday, should I send email to follow up tomorrow or how long to wait?

You are not the only task on their work schedule. You have completed the requirements asked of you, so move on and keep up your job search. You contacting them again could be taken as a weakness or sign of desperation. If they call, great.

No matter what country you are in, one thing common to all HR Recruiters is being annoyed by candidates who call to find out their status. You are not the only task on their work schedule. You have completed the requirements asked of you, so move on and keep up your job search. You contacting them again could be taken as a weakness or sign of desperation. If they call, great. Otherwise, you have not wasted your time waiting.