You'll figure out what works for you, don't worry. With my dc1 I used a bouncy chair in toilet/shower etc. Dc2 kind of lives in a sling/carrier as I need to run round after dc1! Dc2 spent the majority of the first few weeks just being held or she screamed the place down! Now she is 4 months and goes to bed about 7 with a monitor and we cook/eat downstairs while she sleeps.
OP, are you assuming baby has s 'bedtime' and goes to bed upstairs early evening while you are downstairs?
That does come, but not yet. As well as SIDS advice against that before 6 months old, a young baby is often still 'napping' during early evening, rather than having the big block of sleep of nighttime.
We used to do bouncy chair for daytime naps - so from 7am - 10pm ish when I went to bed.
At a wake up that happens somewhere around 6-8pm we used to 'do bedtime' - change into night close, bath if needed etc. But continue naps in bouncy chair.
Then at any wake up that happens at a time I'm ready to go to bed (so 9.30-11.00, depending how knackered I am), then feed and take baby upstairs with me, to sleep in the cot in my room. Then I brush my own teeth and go to bed myself