So the very first sign is that your soul wounds are fully healed and physical separation does not bother you anymore and that physical pain in your solar plexus chakra or in your heart chakra has completely gone and you don't feel jealous towards your twin flame and karmic partners of your twin flame in 3D physical reality.
Second sign that you have is that you start having that sense of inner peace all the time. You feel a kind of strength in your inner being. You feel that now nothing can shake your inner peace but on the surface yes sometimes you can out of habit feel a bit disturbed or affected by external forces but deep inside you always remain untouched and pure by the happenings in your life.
Third major sign is that you start feeling that natural flow of energies. You feel yourself in a divine flow and you start understanding the wisdom behind everything that is happening in your life and everything that has happened in your life.
Now the fourth major sign is that you start taking responsibility of everything that happens around you in your 3D reality.
That's because you have opened the door of your inner world and you have realized that everything good or bad manifests in your reality because of your inner alignment of your soul and you don't blame for your failures other people like your family members or your work environment, your colleagues or planetary alignments.
I find it really funny that when some people don't find anything to blame they start blaming planets and stars and other cosmic beings that their direction is affecting you negatively or like that. I would say that they are very benevolent beings and they don't believe in punishing people or any other beings.
So you cannot tap into the new age consciousness with this kind of duality or with this kind of blaming energy. So whatever happens if you are heading towards the union then whatever happens it happens because your soul is experiencing it. It's because of the alignment of your soul and realization of inner alignment is the biggest sign of union.
The fifth sign of the union is that you have transcended the consciousness of attributing things as good or evil and you are fully above from this divide of duality.
You know that is a trick of our ego. Ego feeds on duality. It shows you bad or evil things so that you can feel yourself good or divine.
One thing you need to remember is that this whole world and everything is divine and if a guru keeps telling you that this is wrong this is bad this is good and this is evil then I'm sure that they are living in a duality and they obviously have not experienced any kind of union nor inner nor outer union in a 3d plane because the first it is one of the major signs that duality breaks down when you experience union everything around you becomes divine and you have only love for everything and duality completely breaks down. So that's also a major sign that you are heading towards the union.
The sixth major sign of the twin flame union is that you become desire free and you find your twin flame all the time inside you and you don't feel separated from them and you always stay connected to them you understand each and every action of them and they don't trigger you at all and you feel unconditional love for them all the time no matter if they are with you or with someone else in the physical plane.
The seventh major sign is that you don't remain codependent sexually and emotionally to your twin flame and you remain happy all the time and you feel that external world is not at all causing happiness and you feel that happiness actually flowers inside you and you reach at that inside place where you see that the happiness is generated by your being inside you.
One of the most major signs is that you feel a direct connection to the source and you don't remain dependent on your angels or spirit guides or something like that you feel a direct connection to the source and yes you are worthy of being directly connected to the source.