If he's still with Cleo by the end of 2018, then they'll set a wedding date in 2019, with the ceremony to take place in Iowa. The reception will be in New Hampshire, at the McIntyre-Shaheen fundraising dinner, at which Booker will announce his candidacy.
Booker will invite all of his Senate friends to his wedding party, like Elizabeth Warren, Kirsten Gillibrand, Kamala Harris, and Chris Murphy, and will demand that they debate him at the reception whenever the guests clink their glasses with silverware.