You can do any job before getting license, drive a cab, security, trucking, retail jobs etc. Getting assistant job for boys is super tough though not impossible if you know some dentist who has clinic. Dentistry is far different here then in india or other countries. No dentist would want someone who doesn't know how things work to come close to patients and make them uncomfortable. Most of them prefer girls to work as assistant and front desk receptionist. May be patients feel more comfortable and secure with girls working around.
Be prepared to do survival jobs first. Make sure you have access to around $40k if you want to challenge ndeb for license. It doesn't include living expenses. Many of my friends did it and they are close to 50k in debt now. If you start with less funding you would eventually lose it and won't reach anywhere. Getting into Dentistry is more about being well funded than being well educated or sharp minded. Jobs for ndeb licensed dentists are difficult to get if not rare. They got paid less in the start compared to dds graduates. They have to learn many aspects in clinic for atleast 2 years to fully understand how Dentistry is being delivered.
I was doing survival jobs for one and half years but now I got acceptance in DDS. Volunteered as Dental assistant for one year unpaid. Know almost all aspects of clinic but still no one was ready to hire me as assistant. Few desi dentists agreed but they pay shit so you would be better off doing some other jobs.
Have a set plan, access to funds and be ready to work, study, volunteer and improving your conversational English to be successful. Doing 10-12 tasks over and over again for clinical exam will give you license but won't makes you a successful dentist. It requires patience, hard work, ready to accept criticism and always be humble to fellow dentists and patients. It's service industry so patient's say is always held supreme. Reputation once tarnished would eventually destroy career.
Start with volunteering and learn from there. Most of all , must not do the common mistake Indians do, they feel being entitled to something here being a dentist back home. Believe me, most of our Indian curriculum doesn't even teach how to make acceptable class II amalgam. They don't even tell the proper burs to use for different preps. So Must avoid this . Be humble and be ready to learn and help.
Good luck.