Is it okay to do one upgrade at a time? Any tips

Planning to upgrade my GS of Claris to 105 pero pa-unti para hindi mabigat at abang sa marketplace if my mura haha. Probably every pay day para di biglaan 😂

Thoughts on this sequence or may better way para makamura.

1. RD
2. STI
3. FD
4. Crank
5. What else to add?

Sa brake, baka same lang since Caliper lang sya.