Does an enchantment that says 'at the beginning of your upkeep' trigger if you just played it on your upkeep?

Triggered abilities that say 'at the beginning of your upkeep' use the upkeep step as their trigger event. Specifically, they trigger when the upkeep step begins — that is, at the moment the step starts and the game checks for triggers (CR 502.2). If the enchantment didn't exist on the battlefield at that moment, it simply wasn't around to 'see' the trigger event occur.

Under CR 603.2, a triggered ability only triggers if its trigger condition is met while the ability exists on the battlefield (or wherever it is required to be). An enchantment that enters the battlefield during your upkeep arrives after the beginning-of-upkeep trigger event has already been checked and passed, so it misses that window entirely.

This is different from 'at the beginning of your end step' triggers, but the same logic applies to any 'at the beginning of [phase/step]' ability — the permanent must already be on the battlefield when that step starts in order to have its ability trigger that turn (CR 603.3).

Concrete example: You cast Utopia Sprawl (which has no upkeep trigger, but imagine an enchantment that says 'At the beginning of your upkeep, draw a card') during your upkeep step. Because the upkeep step had already begun before Utopia Sprawl entered the battlefield, the trigger condition was not met while the enchantment existed. You will not draw a card this turn; the ability will first trigger at the beginning of your next upkeep.

In summary: for 'at the beginning of upkeep' triggers, the permanent must be on the battlefield at the very start of that upkeep step. Entering later in the same step means the trigger is missed for that turn.