My first pond was a lot like that one--250 gallon container pond that I knew wasn't necessarily showy and didn't have a lot of space, but I loved it so much anyway. It doesn't take a lot to make something wonderful to enjoy! I didn't even have the nice stone edging like you do. And I love the decorations!
I'm glad you have plans to create a bigger pond! I am not sure how long very young koi can stay in a pond that size (I keep goldfish, not koi), but the sooner they're in more water, the better. Plus ponds are just awesome.