I can't tell if the start position is BG or not. It looks like there's a dot just left of the settlers foot. The reason I bring it up is that moving the settler N will lose the bottom BG. But then, as nice as the surrounding area looks I'd be willing to bet there are more somewhere N, NE or NW of start. Now that I think about it, I'm likely to move the settler N in any case, so why not move settler N first? If I see the the river turns W or SW, I can then move worker W, otherwise, he can stay in place. <EDIT> On further reflection, if the settler doesn't see any more BG after moving N, we could even move SE on the second turn to make sure we get both of the visible ones. The worker would road the start tile in this case meaning the extra settler move wouldn't cost us anything more than 1 turn of growth/prod. </EDIT>
If worker stays in place, I would road (since I can't irrigate right off), irrigate, move NW, road BG to bump up gold, move SW, and irrigate wheat. This will irrigate the wheat just as capital expands and can use wheat. Then road wheat, move NE and mine BG, then look for another BG. Roading that first BG will be nice because captial will grow just after it's roaded, giving a non river spot for a citizen to work. With luck there will be a BG on the river as well and production will just zip along.
For a 20k game, if you use the capital as the 20k city, the NE spot is probably better, owing to the 4 hills and 2 BG you'd get.