Tevilah on Wednesday night is acceptable for a Sunday night wedding, since it is considered within the window of
four days before the wedding.
While there is a preference to immerse as close to the wedding as possible, if there is a compelling or personal reason, immersion within four days of the wedding is permissible. There is no need to perform any further bedikot after the immersion.
Please feel free to get back to us with any further questions.