Odin is skilled in the art of psychological warfare. The way he treated the Jotnar is a perfect example of this (and so was Bor before him, with the Dark Elves). Imperialism 101: colonize your less industrialized victims after winning a war against them. School your children in their “innate inferiority” and skew your culture to be dominant over theirs, a symbol of your “enlightenment.” Play the “benevolent parent” (how convenient the traditional Norse mythological title of “Allfather” becomes) over them, implicitly rendering them the monstrous and ungrateful enemy should they revolt. Leave them economically dependent on you as well. Make your “peace treaty” nominal only.
So back to your question: The way Odin treats Loki is a microcosmic version of the way he treats Loki’s entire race of origin. It’s no wonder Loki has internalized racism to cope with, which he externalizes as inflated self importance, hostility, and “greed” for power (let’s not even go there with that incorrect adjective). I would never say Odin never loved Loki. That’s inaccurate. Odin did, as far as Odin is capable, love Loki. But Odin didn’t love Loki ENOUGH. That love was contingent upon unquestioning obedience (and so was his love of Thor, btw, just refer to TDW, when Odin told the Einherjar that they could kill Thor if it mean stopping him going to Svartalfheim). Odin absolutely wanted to get rid of Loki as quickly as he could, once his younger son proved he was willing to fundamentally disobey his orders and his PLANS for Loki’s role in Asgard’s political scene. As soon as Loki proved himself more than a complicit shadow of Thor, it was time to make Loki a convenient example of what happens to those who commit treason. EVEN THOUGH Thor committed treason first (going to Jotunheim to start a war), and Thor’s buddies committed treason against Loki, made RIGHTFUL KING BY FRIGGA, as well, and were NOT punished. The difference here is that Loki does not fit Odin’s view of a complacent son (for all his own disobedience, Thor still essentially worships his father) and a “correct” type of Asgardian. Loki is an inconvenient truth.
So Odin stalls the trial just long enough to make the deliberation look official (and yes, given how much Frigga protested when Thor was banished temporarily but given relative freedom, I am SURE she protested to Loki being sentenced to life in prison). He then hastens to get it over with, BUT MAKES SURE TO MAKE IT PUBLIC AND EXTREME: egregious chains on Loki’s neck, wrists, waist, AND ankles, the whole shebang.
But I think it’s even more insidious: I don’t think he conducted the “trial” (with utterly NO witnesses to speak on Loki’s behalf) hastily just to get it done. I think he waited until Thor was in Vanaheim so that Loki would have no advocate whatsoever. Sure, Frigga was there. But Odin never listens to Frigga; he tells her “Enough!” when she simply approaches Loki to ask him not to goad his father!!! And he often shows her point of view flagrant disrespect, to the point that she knows she can’t even physically visit Loki’s prison cell without rousing Odin’s further ire against his son. So who is left? Who will people listen to, who will–and in fact, DOES, later on in TDW–garner enough public loyalty to instill doubt in Odin’s supreme authority, about Loki or anyone else?
So there you have it. The reason why Odin delayed the trial? he was waiting for Thor to be absent, so that Loki couldn’t use their brotherly bond to weaken Thor’s resolve and get Thor to say, “Hey, wait, let’s think about this.”
Because make NO MISTAKE about it: Odin gaslights Thor, too. Odin renders Thor DEEPLY dependent on Odin’s opinion. Odin is the reason why a wedge was driven between Thor and Loki from childhood. Odin raised Thor devoid of criticism and accountability, then thrust him into the public light, then punished him for acting atrociously. My point being, Loki’s delayed trial is just one more example of Odin keeping sure to keep his sons from forming an emotional alliance against him, and, again, challenging his absolute authority as the Allfather. No one clings to power like Odin. He makes Loki, at his Tesseract-crazed worst, look like a baby deer.