Low-Parfait177's journey

I recently started a part-time managerial position at a restaurant, expecting to earn $25/hr as advertised in the job listing. However, I was informed by the owner that I would begin at minimum wage. I accepted this because I was thrilled to secure a job. Early on, we discussed my wage, and the owner mentioned that once I got a good handle on my responsibilities, we could talk about a raise. Now that I've been working there for a while, I feel comfortable with my tasks, even though I still make minor mistakes occasionally. I'm hesitant to ask for a raise for a few reasons: first, I don't want to seem ungrateful since the job doesn't require specialized skills; second, my workload is similar to my coworkers who are also earning minimum wage; and third, business is slower right now, so I feel guilty about asking for a wage increase. The owner did indicate that they would consider raising my pay to $25/hr in September, but I would really like to discuss this sooner. My role involves kitchen responsibilities and setting up for the restaurant, which is about an hour more than what servers do, but the work is generally the same. I'm looking for advice on how to approach this situation.