If you are talking about the auto incrementing id column of your orders table then you can set the auto increment value in MySQL Administrator for that table, just open it and in the advanced options you can set the auto increment value.
You can also do this with an SQL command like this:
ALTER TABLE orders AUTO_INCREMENT = 1000;
If you change the auto increment initial value like this keep in mind the limit to this field will be 4294967295, not likely that you will reach this limit but it is something you should be aware of.