The total offering amount under Rule 504 can be up to $1 million in a 12-month period, less the aggregate offering of all securities sold within 12 months before the start of a 504 offering. So, if a company has raised $100,000 in private money in the previous 12 months, it can still raise up to $900,000 without being accused of breaking the rules, or integration.
If they start a 504 in April they must subtract money raised in the prior 12 months.
The start date has nothing to do with it, the 12 month period is rolling.