Hi carolcavaleiro,
Thanks for reaching out.
Advanced Ads does not provide any specific options regarding initial or polite loading. If you run Advanced Ads Pro, you can enable lazy loading for particular placements to ensure that ads assigned to them start loading when the user reaches a definable distance to the ads, for example, 600px.
There are no limits regarding the file sizes. When you use image ads and save the files on our server, your WordPress settings determine the maximum file size.
I always recommend reducing the size of self-hosted image ads as much as possible not to harm your page speed.
In our manual about CLS, you can find more suggestions about handling ads and page speed.
Best regards,
Joachim