What are the advantages of an online kitchen design service over simply calling somebody in to do it for you? Cost is one benefit: it is a lot less expensive to do it yourself online than for somebody to come to your home and do what you could do just as easily yourself. Another benefit is that you get exactly what you want, and you can't blame anybody else if it is not to your liking.
The placement of your work triangle should be the next step in designing your kitchen layout. The sink, cooking surface, and refrigerator need to be situated within easy reach of each other to allow your kitchen to work smoothly. Here, again is where an experienced kitchen designer can be a valuable partner in the design of your kitchen. They have the experience to know what will and what will not work efficiently, and could keep you from ending up with a kitchen which does not meet your needs. A good kitchen designer will know if your kitchen would work better with an island, or maybe a peninsula, or a movable cart or nothing at all. These are design items that need to be addressed early in the process, and will make the whole design process successful.