When it is financed, you will still take it into earnings at that time. Prepaid interest is reportable and your odd days is "collected" up front. Here are the IRS instructions for prepaid interest.
Report prepaid interest (other than points) only in the year in which it properly accrues.
Example. Interest received on December 20, 2014, that accrues by December 31 but is not due until January 31, 2015, is reportable on the 2014 Form 1098.
Exception. Interest received during the current year that will properly accrue in full by January 15 of the following year may be considered received in the current year, at your option, and is reportable on Form 1098 for the current year. However, if any part of an interest payment accrues after January 15, then only the amount that properly accrues by December 31 of the current year is reportable on Form 1098 for the current year. For example, if you receive a payment of interest that accrues for the period December 20 through January 20, you cannot report any of the interest that accrues after December 31 for the current year. You must report the interest that accrues after December 31 on Form 1098 for the following year.