From the FAQ - so yes you can test tomorrow if your sailing says 2 days befoe
How do I calculate which days I may take my pre-cruise COVID-19 test?
When calculating which days you can take your test, be aware that the day you set sail is not counted as one of the days, unless the country of embarkation stipulates that the test be taken within 24 hours of arrival.
For example, if you are setting sail on a Saturday, and you are required to test 3 days before your sailing, you can take your test on Wednesday, Thursday, or Friday; and for 2 days in advance, you can take the test Thursday or Friday.