Anyone presenting a toast should be asked to prepare in advance. The Best man presents the first toast, which can be immediately after the cake cutting ceremony but this is not necessarily so. (Note; when you are the person being toasted, you do not drink out of your glass.) The wedding host (traditionally the father of the bride) toasts the couple. Other parental figures of the couple toast the couple.
Other good times for toasts are before or after the first course is served or after the main course has been eaten. If toasts are offered after the first course, then the cake cutting ceremony should be delayed until after the guests have completed their main course.
After the Best man has presented his toast, then the father of the bride may offer a toast to the bride and groom and to the groom's parents, welcoming the union of the two families. The Groom may then toast his new wife and both sets of parents.
These first three toasts may then be followed by toasts from other special guests.
Normally your best man is the ‘master of ceremonies’ at a wedding reception so the toasts start with the best man.