As a general rule, use the verb "estar" for temporary things, things that are valid for a period of time.
1.- Location - use the verb "estar" in order to talk about the location of places or where someone or something is located.
Londres está en Inglaterra.
London is in England.
Los padres de Alberto están de vacaciones en Australia.
Alberto's parents are on vacation in Australia.
El vestido rojo que buscas está en el armario.
The red dress you are looking for is in the closet.
2.- Dates and Seasons - When telling the date with the verb "estar" always use the preposition "a" after the verb. When talking about the seasons of the year, use the verb "estar" followed by the preposition "en". Don't use the verb "estar" to tell the time.
Estamos a jueves.
It's Thursday.
1.- Location - use the verb "estar" in order to talk about the location of places or where someone or something is located.
Londres está en Inglaterra.
London is in England.
Los padres de Alberto están de vacaciones en Australia.
Alberto's parents are on vacation in Australia.
El vestido rojo que buscas está en el armario.
The red dress you are looking for is in the closet.
2.- Dates and Seasons - When telling the date with the verb "estar" always use the preposition "a" after the verb. When talking about the seasons of the year, use the verb "estar" followed by the preposition "en". Don't use the verb "estar" to tell the time.
Estamos a jueves.
It's Thursday.