Any new home that isn't complete will likely not be eligible for standard financing. Most lenders will require a home received it's certificate of occupancy (CO) before doing ANY type of loan on it.
Yes, it's true, a 203k loan requires the CO to be in place and have been in place for one year before rehab financing can be used.
Your only other standard option is a HomeStyle loan and most lenders will have the same requirement (the CO) as well.
The only way to close on a home like this for sure is with a true construction-rehab loan which will be a portfolio lending product (local or maybe regional bank or credit union). Lenders right now don't have much of an appetite for construction lending which is why you see so little of it and also why you'll see so few new homes outside of a major development. Keep in mind I'm not saying construction loans aren't out there, "construction-rehab" is the part that'll be the challenge to find and some lenders who offer these products have minimum loan amounts as they want to minimize their exposure since the majority of the construction was done outside of their control.
Good luck! If you need additional information on rehab lending, I have many posts about it, just look through the Q&A or my blog(s).... more