If you skip enrollment this year, you can enroll in a Wagmo Wellness plan during your next annual open enrollment. You'll typically need to actively opt in through your employer's benefits system at that time, since skipping one year doesn't automatically re-enroll you the next.
Once your new plan year starts, your Wagmo Wellness plan only reimburses eligible expenses incurred after your plan effective date. Veterinary visits that happened before that date are not eligible for reimbursement.