Cohabitation visa process with Belgian citizen

Hello,

you're mixing things.
Cohabitation is a declaration to the municipality, you can sign it anytime you want.
It will not change the marital status like a wedding would, but it will change the family composition. Meaning that in the laws point of view, you'll be family members.

Based on the fact that you're a family member of an EU, you can then request a family reunion (the F card) from Belgium IF you respect the conditions stated by the laws. (Basically you must live together for 1 year, or known each other for 2 years &  5 trips to see each other and 45 days spent together..., 21 years or more, ...)


What matters in your case is the family reunion process based on the fact that you'll be able to sign the legal cohabitation.
Basically it depends if you can proof that you have lived together at the same address for at least one year: Certificate from the commune, Electricity/Water/phone bill, ...

If you can't proof it, then you'll have to wait the birthday of the 2nd anniversary that you met each other, before requesting the family reunion.
(and provide proofs / pictures / flight tickets / phone call history / vacation together / ... that you met each other 2 years ago and you kept in touch)


Once you request the family reunion, the full process takes 6 months but you can legally stay in Belgium during the process.
You'll receive the annexe 19ter and the orange card (temporary resident card) (no work permit needed anymore).
You'll have to provide your full file 3 months later at the commune, they'll send it to the immigration. Immigration has 3 more months to refuse your resident permit.