Essentially, you can track accrual in whatever way will work best for you as long as you are meeting the minimum standards laid out in the legislation.
You must meet the equivalency test laid out in the legislation - this means that whatever rate of accrual you choose to provide must be at least as rapid as one hour earned for every 52 hours worked. Furthermore, employees must be able to earn up to at least 24 hours per year in 2017 and 2018, and up to at least 40 hours per year in 2019 and thereafter.
If you wish, you can choose to track time for your employees at each pay period. You could also track time on a monthly or quarterly basis. Note, however, that the law does require that your employees have access to the paid time they are earning in each quarter, should they need it.
Perhaps the simplest way to offer your paid time benefit will be to provide it in bulk annually. In their first year of employment, employees will earn time, but you do not need to permit them access to their bank of paid time until they have worked for one full year. At that point, they will have a full “bank” of time, which you could simply renew at the start of each year, ensuring that employees have access to 24 hours of paid time off to use in 2018 and up to 40 hours in 2019 and thereafter. This annual bank method will work best for full-time employees or for part-time workers with consistent schedules.
If you have part-time employees and wish to provide only the minimum requirement, you will likely want to track hours as they are worked according to the minimum accrual rate of one hour earned for every 52 hours worked. In this case, you may tally the accrued time each pay period, monthly, or quarterly - whatever is simplest for you. Note, however, that if you tally the accrued time quarterly, employees must still be able to use the time they have earned in the current quarter, if they need it.