Here is Rev. 20:2- 3. The first verse is for context. My main point comes from the second:

"And he laid hold on the dragon, that old serpent, which is the Devil, and Satan, and bound him a thousand years,

"And cast him into the bottomless pit, and shut him up, and set a seal upon him, that he should deceive the nations no more, till the thousand years should be fulfilled: and after that he must be loosed a little season."

I just noticed something here the other day. Do you see the two tenses?

First the Past tenses: "He laid hold", "bound him", "cast him", "shut him up", "set a seal upon him".

Then we have the Future tense: "after that he must be loosed".

The point is this. John wrote this around 95 AD. He describes these actions from that time vantage point. The past tense things already happened: Satan being bound, shut up, sealed. The future tense has not happened yet at AD 95. That still awaits fulfillment.

If this were all future, as Dispensationalism insists, normal grammatical usage would require all future tenses: "He Will bind him", etc.

If this were all past, as Preterists, for instance, maintain, you might reasonably expect all past tenses.

At any rate, it makes no sense to either system to have both past and future tenses to describe these events.

Amillennialism has the answer that fits best here: Satan was bound by Christ's earthly ministry and death on the Cross (Luke 10:18- 19; 11:20- 22; Mark 3:27 "binding of the strong man" (=Satan); Daniel 9:24 "restrain (or "shut up") transgression" - NOT "finish"). He will be loosed for a very short while just before Christ's second coming.

Satan was bound at the Cross, but he will have a last slackening of restraint just before the end.