Why is it important to apply on April 1st or as soon as possible, for the H-1B visa?
By law, there are only 65,000 (for professional bachelors) and 20,000 (for advanced degree professionals) capped H-1B visas available each year (there are certain H-1B visas not subject to the yearly cap—see link below). The USCIS starts accepting H-1B visa applications on April 1st, for the visas that will be issued in October of that year. In the past, H-1B visas have ran out early in the year, so it is suggested that you apply as close to April 1st (or as soon as possible), to have a higher chance of there being visas available.