I don't really have an order in mind, I just wanted to sort which pram and car seat we wanted by about 15 weeks so I could keep an eye out for sales and discounts. My deadline to buy/order if we haven't already is 34 weeks.
I'm looking at any second hand sales and picking up stuff as and when which gets offered on local groups or when people ask me if we need things. So we've already got a baby bath, changing table, play gym thing, a few clothes in random sizes, some towels someone gave me. Then SIL has bought us a baby front carrier and a bumbo, a changing mat, another bath (!!) and about 10000 toys which I was a little bit overwhelmed/sad about all of, but I am feeling better about today. DH is going to use the cheapo carrier and I'll get my fabric sling and we'll go and find a structured one we like when our individual ones get too uncomfortable. Other SIL offered to buy us a particular bedside cot which I wasn't sure about but we've now said yes to.
Only other timescales I've estimated are:
Weeks 22-24: Properly plan + cost room - furniture, colour scheme, curtains etc.
Weeks 25-30: Decorate room (We're only doing this because we've just moved so we HAVE a room to decorate - and want to get it done before baby arrives because it will be easier.)
Week 30: Choose hospital (relevant for what to bring?)
Weeks 33-34: Find out and buy any remaining contents of hospital bag/needed supplies
Week 36: Pack hospital bag
Weeks 34-36: Work out if we've got enough clothes and if not: SHOP!!!
These are arranged around paydays and likely maternity leave start plus school holidays so adjust as necessary. I think I'm doing all of this planning as a displacement activity 
I think - somewhere to sleep, car seat, random bits like towel/bath/changing mat, blanket or two and enough clothes to wash are basically what we need for the first few days and everything else - nappies, wipes, muslin cloths, maternity pads, breast pads/BF bras - all of this will be covered by the hospital bag list so I don't think anything is going to be left out? It seems like we're going to have a few unnecessary but nice extras as well with the way things are going so I think we should be good.