The emphasis is the schedule for now, rather than the need to talk.
For example, if you had planned to speak with the boss after finishing writing a report, you would use "Now I need to speak with the boss". If a problem arises and you need to speak with the boss urgently, you would use "I need to speak with the boss now". It's the same for Spanish.
Jefe is a male boss and jefa is a female boss. Both are alright to use, though if you're not sure which one duolingo wants at the time, check to see if the adjectives used for the boss are masculine or feminine (cansado vs cansada, etc) as well as the determiner used (el/los vs la/las). In typing exercises, either of them are fine as long as you use the correct gender for adjectives and the determiner!