This adds clarity to the card, because the splitting of a blastocyst can result in either monoamniotic or diamniotic twins. Cleavage of the blastocyst during days 4-8 results in monochorionic, diamniotic twins. Amnioblasts develop within the blastocyst after implantation and development of the bilaminar disc, so cleavage of the blastocyst during days 8-12 results in monoamniotic twins. The cell differentiation of embryoblast -> epiblasts -> amnioblasts occurs after implantation.

Sources:
1. First Aid 2024, page 630, Early Embryonic Development:
"Week 2 - Formation of bilaminar embyronic disc, two layers = epiblast, hypoblast" Diagram shows bilaminar disc development after implantation (listed days 6-10) and before gastrulation (listed days 14-16).

2. Amboss article Embryogenesis > Embyroblast and Trophoblast Development > Embryoblast
https://next.amboss.com/us/article/vo0AdS?q=epiblast#Y09f94653421b45461765f42bc63a5508
"In the 2nd week of embryonic development (days 8–14), the embryoblast differentiates into two layers (epiblast and hypoblast), termed the bilaminar disc. After formation of the amniotic cavity and yolk sac, the bilaminar disc is sandwiched between them.
Embryoblast → bilaminar disc
Epiblast: columnar cells adjacent to amnioblasts → form the amniotic cavity → forms the embryo (begins the 3rd week of embryonic development)"

3. Amboss article Multiple Pregnancy > Classification
https://next.amboss.com/us/article/Yl0nvT?q=twin#Y4b8806a33f284fb1615339ebd5fbcbbe

Diagram in image as well as chart stating "Monochorionic-diamniotic - The twins share a single chorionic sac (the twins share a placenta) but have a separate, individual amniotic sac. - Day 4–7 after conception
Monochorionic-monoamniotic - The twins share a single chorionic sac (the twins share a placenta) and a single amniotic sac. - Day 8–11 after conception" Image shows mono-di coming from blastocyst in days 4-6 and shows mono-mono developing days 8-13 after amniotic sac differentiation.

https://next.amboss.com/us/article/vo0AdS?q=epiblast#Y09f94653421b45461765f42bc63a5508
4. Amboss article Embryogenesis > Overview > Embryonic Development
"Day 6
Implantation (embryology) of the blastocyst (most commonly into the anterior or posterior wall of the uterus).
Days 6–14
The bilaminar embryonic disc develops (2 layers): epiblast and hypoblast
Epiblast → amniotic cavity
Hypoblast → yolk sac, lining of chorionic cavity"