at one time vs before

at one time

• formerly 

• simultaneously, at once. 

before

• Earlier than (in time). 

• In front of, according to a formal system of ordering items. 

• In store for, in the future of (someone). 

• At a higher or greater position than, in a ranking. 

• Under consideration, judgment, authority of (someone). 

• In the presence of. 

• In front of in space. 

• At an earlier time. 

• In advance. 

• At the front end. 

• Rather or sooner than. 

• In advance of the time when.