So, despite this being very individual thing we can try to find some suggestions that are scientifically based.

For one, many experience a period of heightened infatuation upon starting a new relationship whose symptoms are not unlike substance addiction. This may lead to some poor decision making when it comes to long term commitments, as well as changed behavior and tolerance toward partner’s behavior.

I don’t have any hard numbers here, as with any hormonal response it is going to be rather individual matter. I encourage you to look up existing research for anything more specific, but my vague recall is of there being three distinct phases of 2 months, half a year and two years from the start of relationship respectively. I would generally recommend avoiding any significantly life altering decisions in the first couple of months at very least. For brief overview of the topic I’d suggest:

https://www.multiamory.com/podcast/177-brain-on-love

There are many more factors that are going to have much more significant impact than age of relationship per se, from economic situation to major life events. You will probably want to look at this discussion of the topic:

https://www.multiamory.com/podcast/209-to-cohabitate-or-not-to-cohabitate

One big take-away I remember from it is: don’t settle for less private space than you would with a roommate. You may think you can take up less because of love but that’s generally not true and is likely something that can actually grind your relationship down. And if it doesn’t work out it’s better to be able to resolve the matters amicably rather than constantly stepping on each others’ toes.