Initial development was on the Intel i860XR RISC processor, switching to the MIPS R3000 in late 1989, and then the Intel i386 in 1990. Later it ran on DEC Alpha, PowerPC, Itanium, x86-64 and ARM. (Wikipedia)
If you have developed a portable OS, it really doesn't matter whether ARM was first or last or inbetween.
If you have developed a portable OS, it really doesn't matter whether ARM was first or last or inbetween.