Early in the Galactic Empire, Clone Wars era armaments remain in use as new Imperial era technologies are slowly rolled out to replace the last relics of the Republic power. Known parts of the transition can be outlined as follows:
- Clone Trooper -> Stormtrooper
- AT-RT -> AT-ST
- AT-TE -> AT-AT
- V-Wing, Actis Interceptor, ARC-170 -> TIE Fighter, TIE Interceptor
- Y-Wing -> TIE Bomber
- Venator Star Destroyer -> Imperial Star Destroyer
- LAAT/i -> Sentinel-Class Shuttle
(Original question paragraph here deleted. Please see the reworded version below.)
Edit: To clarify, I don't want to know when each Imperial military weapon replaced its older Republic version just for the sake of it. The primary question is when did Imperial-era military technology replace their Republic counterparts? To quote a 501st stormtrooper:
Armed with deadly new weapons, blazing new ships, and shiny new armor, our presence let the galaxy know that the days of the Old Republic were well and truly over.
When did the Galactic Empire complete its transition to "deadly new weapons, blazing new ships, and shiny new armor"? That is the real question, and phrased this way that would be a valid singular question without needing to be split up.
But the answer would still be too broad at this point: There are a lot of Republic tech whose replacement is ambiguous/unidentified (what replaced the SPHA-T?) or they remained active and never retired (at least one Juggernaut served during the Battle of Hoth in canon). So the above bullet list serves to set boundaries on the scope to be addressed when answering the main question. If I split this question weapon by weapon, it'll be fragmenting my actual, main question by too much and scattering its answer to the winds.
So, I guess I should at least rephrase the question: Using the above list as the sole representation of the Galactic Empire's military's transition from Republic era weapons to Imperial era weapons, when in canon did the Empire conduct and complete this transition?
The answer should be based on when the Imperial weapons entered service and the Republic weapons fully retired. Where that is not possible, the answer should state when the weapon in question first/last saw action under Imperial usage (esp. for tech retained by the Rebellion such as the Y-Wing and the LAAT/i - Rebel usage doesn't count).