Conocí Conocía

[BobRitter]

Creo que esto es correcto. Por favor corríjame si estoy equivocado.

Conocí a Juan in Mexico. I met Juan in Mexico.
Conocía a Juan in Mexico. I knew Juan in Mexico.
USE preterite for met in the past and imperfect (conocía) for knew in the past

Estoy teniendo demasiado divertido!

[AngelicaDeAlquezar]

Yes, that's right. If you change the tense, you change the meaning of the verb.
I would like to introduce a slight nuance though:

"Conocí a Juan in Mexico" clearly says "I met" him and where. This is a one-time event, since you cannot be introduced to someone several times and we know the specific place where that event took place.

Now, if you say "conocía a Juan", you're saying "I used to know Juan"; that's alright and it's a natural construction.
However, the sentence "conocía a Juan en México", introduces a peculiar situation: you used to know Juan in a specific place (Mexico), but after moving to another country you don't know him anymore. That's a bit strange.

¡(Try not to forget opening exclamation and question marks; they're important) Estoy teniendo demasiado (Although in English "too (much)" can be used with a positive meaning, in Spanish "demasiado" implies an unhealthy exess; it's better to change it for "mucho" or "muy", depending on the expression.) divertido (Heads up: "divertido" is an adjective, but for the kind of construction you wrote, you would need a noun. The corresponding noun is "diversión". However, we wouldn't speak like that; the usual expression when we are having fun is "me estoy divirtiendo mucho")!

[BobRitter]

Gracias Angelica

I met Juan in Mexico before he was famous.
I knew Juan in Mexico before he was famous.

Conocí a Juan en México antes de que fuera famoso.
Conocía a Juan en México antes de que fuera famoso.

....de que fuera famoso. Subjectivo - Me encanta.

¡Me estoy divirtiendo mucho!

I speak English, have a college education and consider myself smarter than the average bear (from Yogi Bear cartoons) but I now know far more Spanish grammar then I ever knew in English.

[Rusty]

Originally Posted by BobRitter

....de que fuera famoso. Subjuntivo - Me encanta.

¡Me estoy divirtiendo mucho!

I speak English, have a college education and consider myself smarter than the average bear (from Yogi Bear cartoons), but I now know far more Spanish grammar than I ever knew in English.

Subjectivo isn't Spanish. Subjetivo is a Spanish word, but it isn't the denomination you meant to use, either. The subjunctive mood has almost fallen out of use in American English, but it is very much alive and well in Spanish.