There are many pros and cons to seeing each other for the first time in a private or semi-private “First Look” on your wedding day. The more “traditional” approach would be to not see each other until the ceremony, but many couples now are opting to have a staged First Look for several reasons.
A First Look allows full wedding party and family photos to be taken prior to the ceremony. By doing so, it allows you to potentially attend your cocktail hour. For larger wedding guest counts, attending your cocktail hour (and/or having a receiving line) helps you greet many guests without having to table hop during your reception. It also allows you to be fresh for those portraits and family photos, especially on days where weather is a factor. On hot days in the summer and early fall, having a First Look might mean the difference between your wedding portraits looking fresh and vibrant, or hot and miserable.
If you choose not to have a First Look, it is recommended that you leave a little extra time between the end of your ceremony, and the start of your cocktail hour/reception. This way you can still possibly attend part of your cocktail hour. I always try to work as quickly as possible, but if you have given me a large shot list and we only have half an hour because you did a receiving line, you might miss your cocktail hour.
Ultimately there is no wrong answer. I will get your photographs accomplished, and I will be happy to guide you through the process of planning those logistics.