por tiempo

These words let you connect ideas regarding the moment in time when they occurred. 

primero, segundo – first, secondly

Used often in recipes, processes or algorithms, these words are a good way to keep the chronological order in mind.

Primero, unta la mayonesa en el pan. Segundo, agrega el jamón. 
First, spread the mayonnaise onto the bread. Secondly, add ham. 

en primer lugar, en segundo lugar – In the first place, secondly

Similar to the previous one, but more common in formal speeches or everyday conversations. 

En primer lugar, eso no es cierto. En segundo lugar, yo ni siquiera estaba aquí. 
In the first place, that’s not true. Secondly, I wasn’t even here. 

después (de) – after, afterward

Carlos hizo la tarea después del partido de fútbol. 
Carlos did his homework after the football game. 

ya – already

Ya is useful to express that something has already happened. 

Terminé el trabajo y ya lo mandé por correo electrónico.
I finished my work and I already sent it by email. 

todavía – still

To express that something is still happening at the moment, you use todavía. 

Cuando se despertó, el dinosaurio todavía estaba ahí.
When he woke up, the dinosaur was still there. 

todavía no – not yet

However, to say that something has not happened yet, you have to use todavía no. 

¿Ya empezó el partido? Todavía no. 
Has the game started already? Not yet. 

Other useful transition words for time:  

Mientras
While

Por fin
at last

Al final 
At the end

Finalmente  
Lastly

Al mismo tiempo 
At the same time

Para continuar
Next, further

Por último
Lastly

En conclusión
In conclusion

If your goal is to be fluent in Spanish, transition words are a crucial area of study. For that reason, it might be a good idea to keep the following list at hand, as you will always need a good transition word to make your speech and writing sound more natural.