The name of the bride always precedes the groom's name . In social importance, the woman is always first, then males, then children. Traditionally, the man's first and surnames are never separated.
It seems the strict etiquette really applies mostly to the formal stationery, so for other items use your personal preference on what looks and ‘feels’ right to you. Often times a couple is known to friends and family in a certain order and it feels funny to mix that up
What works for you:
It really comes down to you and your wishes, when designing a plaque we look at how the names layout over the surname and how well the letters and graphics balance and fit as a whole. Balance is the distribution of the visual weight of objects, colors, texture, and space. If the design was a scale, these elements should be balanced to make a design feel stable. During the design process all of this is taken into account. When the design is complete a draft will be submitted to the customer for final approval before construction begins.