Should speakers be upgraded before preamp and amplifiers?

OK, let me ask...why do you want to upgrade?  What do you want to achieve sound-wise?  What type of music are you drawn to?  Format?  Do you have a good dealer nearby where you can demo different pieces of equipment to see what each brings to the equation?.  I think you need to start the journey of identifying what it is that you want to achieve and then begin putting the pieces together.  Speakers bring a lot of character to the overall presentation, but then the source has a lot to do with it as the speakers present what is presented to it, even the interconnects and cables can have a lot to do with it.  So, having a good idea of what it is that is important to you sonically is a good starting point.  You cant figure how to get there unless you have a good idea of where 'there" is.

First step is dump that 50+ year old turntable and cartridge!

everything matching well together is key...though sometimes the buying process can be thrown off by a super good deal ...

I try to follow this for next purchase decisions.  Where am I at with everything else and what am I looking to accomplish?  Just a different flavor or are there still basic needs to cover.

https://gr-research.com/priorities-for-proper-system/