At some weddings I have attended caterers only put out little tiny pieces of bread when people wash in the beggining of the meal. After the appetizers are served and the main dish is served the caterers bring out pieces of bread over a kzayis. Can one wash there hands and eat a tiny piece of bread and then eat appitzers and then around 30 minutes later eat the rest of kzayis of bread or should one not eat at the wedding until a chashuv amount of bread is served?
Mishnah Berurah (167:35) writes that it is permitted to speak (to make a hefsek) after eating a small amount of bread (less than a kezayis), yet adds that wherever circumstances allow, it is preferable to eat an entire kezayis immediately. Based on the description of the wedding, it would appear inconvenient to wait until the rest of the bread is served before washing, and doing so would also cause questions of berachos she’einan tzerichos for the appetizers and the main course. It would therefore be permitted to wash and make hamotzie over the small pieces of bread.
Of course, one must ensure that the rest of the bread is eaten later, for several halachic reasons.
I would advice requesting a roll of bread from a waiter, which would solve the problem in the most ideal manner.