Fortuitous means, "happening by accident or chance". You may have worked hard to achieve something. That is not fortuitous.

I think of being in the right place at the right time as fortuitous.

Fortuitous also means unforeseen, unplanned.

I prefer to think of fortuitous as a positive, good-fortune event, or a "happy accident".
But is can also describe and unfortunate event or accident.

Graham Cooke talks about "the suddenlies of God", to describe events like David's anointing by Samuel or Moses at the burning bush. I think that God loves to surprise us with gifts and opportunities and that He sets ambushes for the enemy.