Winston Churchill once described armaments manufacture as a process that yielded nothing in the first year, a trickle in the second, and a flood in the third. Something similar applies to building a tailored clothing wardrobe.
The way I see it, the five day a week tailored clothing wearer needs to add four things a year most years. Oh, he might be able to get by with two or three for a while once he has the basics in his closet, but it takes four pieces a year for most of a decade to build a selection of appropriate clothing for a temperate climate.
Early on, a man wears out his wardrobe more quickly than he does later. Allowing for that wear, a critical mass of 18-25 pieces (that would be something like six suits for summer, winter and if necessary shoulder season, a dinner jacket, two overcoats and four odd jackets) takes seven or eight years. Men living in gentler climes need fewer pieces and the process goes considerably faster.
One way to achieve the required mass is to take the annual clothing budget and figure how much can be allocated to those four yearly pieces. That level of expenditure per item may be disappointingly low, but in the early years those four acquisitions are going to be worn to death and even the best made clothing has a shortened life when it must be worn more than weekly. It is not until the fourth or fifth year of wardrobe building that things begin to ease up.
Of course, whenever I make an assertion like this one, someone throws Anthony Biddle's seven suit wardrobe from 1960 at me, to which I reply that they are forgetting that his closet also contained morning clothes, evening clothes, odd jackets and overcoats totalling about the same number of items.
Try to plan for two things each spring and two each fall.