in what order does a VHDL program run in an FPGA
You have a conceptual difficulty here. VHDL is not a program in the computer program sense, it is a DESCRIPTION how hardware elements are connected. There is no particular order. Once you "program" the VHDL code into FPGA, it creates proper links between logical blocks and configures them. 

Once you turn the power on and configuration bits are loaded into all FPGA areas, all FPGA functional blocks work in parallel, all parts. If you need some distinctive sequencing out of your design, it should be done via so-called FINITE STATE MACHINES, which still run in parallel, but change flip-flop states only on certain signal conditions, on clock-by-clock basis, so it looks like it is waiting for some signals and sequentially executes something.