737 Incog
Not sure how you're arriving at first alternate with just final reserve fuel. Lets say you've dispatched to a closed destination with 2 useable alternates and you've taken plog fuel, ie fuel for the furthest alternate. You have 2 possible scenarios in flight:
1. Destination opens. You make an approach there, you have to go around and divert to Alt 1 arriving with slightly more than final reserve because you had fuel for the farther Alt 2.
2. Destination does not open. You therefore make an approach to Alt 1, you have to go around and divert to Alt 2 arriving with around final reserve fuel depending on the respective distances between the 3 airports.
In each case you've made 2 approaches with a diversion to get to final reserve, same as on any normal day. The only thing you do need to be aware of before you go is the relative positions and distances of the 3 airports but you'd do that for any flight anyway.