checking collision on the moment of instantiating

my goal is to instantiate a projectile from an object and have it ignore that source object.
dont wanna use layers as there is a possibilty for the projectile to travel back to its source and then i want the hit to count.
also, in some situations the projectile might not collide with the source on birth.
for those reasons i want the abilty to know if the projectile is colliding at the moment of birth then i can set it to ignore the collision, otherwise if it wasnt colliding on birth behave normally.
tried a combination of time based checks, but got inconsistent results.
tldr;
need a way to get collision at the moment of birth.

You maybe could run a coroutine with an OverlapSphere starting at instantiation, then enable the collider only when the source is out of reach ?

I eventually solved this by setting the projectile to ignore its source on start, then removing the ignore tag when a set distance away from the source.