I have always followed a system that:
If there is something that I want or need, and it involves different components, etc.
It has never mattered what came first or last.. I just get everything and call it good.
When it comes to rifles [air or powder-burning] they always get scoped..
I also like to find a make/model scope that I like the best, and get multiples of them..
That way, each rifle can have the 'same scope', - helping keep that part a consistent..
Last year, I built two custom match-grade bench-rest "10/22s", and scoped them..
I knew what I wanted for each rifle - ordered erratically, assembled, and got that out of the way.
I also knew that I wanted to go with a few Nikon scopes, ordered 2 1st, and had them on hand..
As soon as those rifles were both done, the scopes were immediately installed.
Then until' now, I also got 6 PCP airguns.. Same deal..
I found out that I liked a specific model of the Discovery brand scope, and ordered 2.
They get swapped around from rifle to rifle so much, I'll have to order a few more now..
A BIG variable for me is: Availability & Price.
I'm usually broke as a joke, so, if/when I have the cash on hand to spend on something,
I scour the net for deals.. If something pops up, I'll jump on it..
For me, doing things this way has always worked.. and worked very well..
I do it with Everything. From big things like vehicles down to smaller stuff for hobbies..

Sam -