I'm guessing based on context here that when you say floating, you mean the initial rate set, but it can change at any time based on something happening (most likely a change in index). In that case, the intro period should 1. The first date the the interest rate may change would be the day of closing, which is less than one whole month.
1003.4(a)(26)The number of months, or proposed number of months in the case of an application, until the first date the interest rate may change after closing or account opening.
5. Non-monthly introductory periods. If a covered loan or application includes an introductory interest rate period measured in a unit of time other than months, the financial institution complies with § 1003.4(a)(26) by reporting the introductory interest rate period for the covered loan or application using an equivalent number of whole months without regard for any remainder. For example, assume an open-end line of credit contains an introductory interest rate for 50 days after the date of account opening, after which the interest rate may adjust. In this example, the financial institution complies with § 1003.4(a)(26) by reporting the number of months as “1.” The financial institution must report one month for any introductory interest rate period that totals less than one whole month.
Generally, when I hear a rate is floating, it means before origination and the initial rate has not been set, which doesn't really have an effect on the intro rate period.