You are close to what I would recommend as best practice. Let me share some findings from my previous rounds of ip warmup.
The easy approach to warmup, is to start with 10.000 emails per batch, maximum twice a week for the first week, doubling your volume every week, until you reach your full list size. Example for a list of 320.000 subscribers:
Certain receivers limit senders to daily volume thresholds until they establish their sending reputation. For example, Hotmail limits new senders to 5.000/day - so you want to ensure, you don’t go beyond these limits. Hence monitoring the performance specifically for each ISP individually, is quite crucial
During the warmup, there are few indicators worth keeping an eye on. The quickest way to discover any abnormalities, is to monitor your open rates across ISP domains. As soon as one ISP either underperforms compared to others, or drops suddenly, action must be taken, slowing down the volume ramp up, or even starting from the same volume as in week 1 - specifically for that ISP. Here are some open rates, where I indicate when you need to perform appropriate actions, due to your emails start being blocked:
There is a a good chance, that Gmail and Hotmail (incl. Outlook.com and Live.com email addresses) make up the majority of your subscriber base. For these two, you have access to additional tools which (reactively) provide you with insights into the performance of your sender (IP/domain).
For Hotmail, we can use Microsoft's SNDS tool, which provides you with an overview of how many emails have been received from your IP over the course of the past days, how many of them have reached the subscriber, the share of subscribers who marked your email as spam, as well as the color indicator showing overall “health” of your IP - translated to how many % of your messages have been filtered out.
To get access to this reporting, log in to https://postmaster.live.com/snds using Microsoft credentials (e.g. Hotmail email account), click on Request Access, and follow the instructions. Have your sender IP address ready, as you will be asked to fill it out! If you are spreading your traffic across multiple IP addresses, remember to add all of them.
For Google, there is an even more comprehensive tool available at https://postmaster.google.com/
Here you can add the domain used as a sender domain, to get Gmail's view on the messages received from you.
Lastly, don't forget about SenderScore from ReturnPath. This is probably the most universal tool, giving you a single indicator, based on feedback from multiple ISPs.
You want to keep your score somewhere between 95 and 99. Scores much below that (<80), will most probably have a negative effect on whether your emails actually arrive in the in- boxes of your subscribers