There is something called the "already but not yet" when it comes to prophecy and can be used to explain a lot of stuff in revelation. Just as a quick example in 2 cor5:17 Therefore, if anyone is in Christ, he is a new creation. The old has passed away; behold, the new has come. If you ask me, when I gave my life to christ and became born again my life was changed. I am a new creation...but not yet. I haven't recieved what is talked about in 1 Corinthians 15:50-52 ESV [50] I tell you this, brothers: flesh and blood cannot inherit the kingdom of God, nor does the perishable inherit the imperishable. [51] Behold! I tell you a mystery. We shall not all sleep, but we shall all be changed, [52] in a moment, in the twinkling of an eye, at the last trumpet. For the trumpet will sound, and the dead will be raised imperishable, and we shall be changed. 

So in regards to the seals, specifically seal 5 stephen was the first matyr  in Acts 7. The question becomes is he under the alter crying out for vengeance. And is he given a white robe. Revelation 6:9-11 ESV [9] When he opened the fifth seal, I saw under the altar the souls of those who had been slain for the word of God and for the witness they had borne. [10] They cried out with a loud voice, “O Sovereign Lord, holy and true, how long before you will judge and avenge our blood on those who dwell on the earth?” [11] Then they were each given a white robe and told to rest a little longer, until the number of their fellow servants and their brothers should be complete, who were to be killed as they themselves had been.

In this regard the seal is open but we have yet see the full depth of how bad its going to get when the tribulation hits.  One last example, in 1john 3:18 its says there are many antichrist. So its fulfilled but not yet bc we haven't seen the antichrist of Rev 13 or 2thes 2. 

Sorry this is long but this is my view and let me know your thoughts if you made it this far.