Nishmat's Women’s Health and Halacha site is a good source for halacha for women's health, and they also answer individual questions. Regarding your question, they write
To avoid a number of problems (see below), it is strongly recommended
that the wedding be scheduled for a date when the bride will not be
niddah. She should choose a date at least one week after she expects all bleeding to have ceased, allowing her enough time to count seven
blood-free days and then immerse in the mikveh before the wedding.
(Unlike a married woman, a bride does not need to wait five days from
the onset of her menses, but may perform the hefsek taharah as soon
as she stops bleeding.) But, since it is impossible to predict
menstruation exactly, it is best to set the wedding date somewhat
later than this minimum.
However practically, if the wedding is set long in advance, or cycles
or the excitement and stress surrounding the
wedding [might] lead to an irregular cycle. Therefore, many brides
take hormones to regulate their cycles, even if they normally
and from here
If a bride is niddah at her wedding, the ceremony is valid but certain
problems arise. First, of course, the couple may not consummate the
marriage until she is able to immerse in the mikveh, and they must
observe all the restrictions (harchakot) concerning not touching,
etc., applicable to a regular niddah. Moreover, the newlyweds may not
even be left alone together, particularly at night.